Okay, quick background:

My recently-purchased Kaiser M715 was rebuilt by Memphis Equipment in 2007.  Small-block Chevy 350 was dropped in, along with a TH350 transmission and conversion to power brakes-power steering.

Engine is from a 1974 Chevelle, rebuilt at time of install.  2-barrel Rochester carb, distributor was switched to a new HEI unit.  Less then 2000 miles since 2007, stored indoors.

Now I have it.  It starts up ( manually operated choke) but idles rough.  It stalls if choke is pushed to off position.  Runs if choke is left open, but it's running rich.  Not sure butit appears not to be firing on all cylinders.  If I drive it, or run the throttle, it will run with the choke off but unless I gun the motor when I stop it will stall.

Pulled the plugs, oily and black on six cylinders, two are dry with normal black/tan color, no wear to electrodes.  Put in new plugs and it seemed to run less rough, burned out a bunch of carbon etc, would ALMOST idle but stall after thirty seconds or so of choke going off.

Checked compression, it is good in all eight cylinders.  Ordered new plug wires and picking up a new dist. cap tomorrow.

Most (all) of my experience with car engines for the last thirty years has been fuel injected electronic engines; last carb engine I touched was a slant-6 Dodge back around 1987.

Checked for vacuum leaks and sprayed carb cleaner inside and out, no leaks and float appears ok but I'm not much of a carb expert.

Any ideas?  I don't have a tach gauge, wondering how to read RPM's to set my idle.  Going to drain gas and change fuel filter to be on safe side.  Truck had been sitting since this January, I bought it in June.

Engine is from a 1974 Chevelle, rebuilt at time of install. 2-barrel Rochester carb

you did the rebuild or it was done before being put in the chevelle? how long was it sitting before you got it? vacum advance hooked up to the wrong spot on carb? sucking air around carb gasket?
choke should open after a couple min running so when warmed up it shouldnt stall with plate removed hell I ran my 71 monte carlo with it removed with no problems.

When the vehicle is driven above idle, does it seem to have smooth acceleration or is it chugging along the whole way?

If you have an EGR valve, check that.

Guy ran this truck as a snow plow the last seven years since the conversion.  When I drive it choke on or off it runs OK, it's geared 5.89 so it pretty much sounds balls-out at any speed over 25mph.  It had been parked for six months when I bought it, when it warms up it runs better then cold, but like I said, if I stop while in drive it will stall unless I give it gas.    I'm going to empty the tank--it's in good shape but the gas is unknown, it had a quarter tank in it when I got it and I put five gallons in it so I could run it while working on it.  Gas tank was cleaned and lined last year, didn't see any crap in the filter but I'll change that too.

Motor was rebuilt, then put into the Jeep in 2007.  Engine looks in good shape, exaust headers are rusty but the block, manifold etc look pretty clean.  Vacuum lines look in good shape.

vacum advance under the dist should go to the vacum pull thats strongest on the carb and I assume it has points that should be replaced and gapped properly and that could be 90% of your problem

I just read where you upgraded the dist sorry.

The distributer was upgraded when the V8 was put in...I'm going to put a new cap and rotor & check the points (if they have points...it's an HEI distributer with the coil thing on top of the cap).

My first thoughts were that I'm not getting spark on all eight plugs.  Once the plugs/wires/dist. cap are eliminated I'm guessing idle and mixture need adjusting...not sure on doing that without a way to measure RPM's.  After that maybe set the timing?  Hoping once I do all this the problem is resolved.

There are no points in a GM HEI distributer

It does not take long at all to gum up a carburator after one has been sitting for a while.  Ethanol in gasoline makes this condition even worse.

I would rebuild the carb.  Should be really easy on a 2 bbl Rochester.

I bet it was running fine before it was parked.  Time and inactivity gets a carb every time.

Don't do anything til you fill the tank with Chevron premium and run it down the road a bit. Some of that may very well fix itself. Also, raise the idle a bit until it will idle down, there is no point in fighting it. Once you have 20 or more miles on fresh fuel, reassess. Usually things won't go too far wrong in 6 mos, they just need run.

Going to empty the gas tank, put in some fresh gas, and sea foam it.  Once I'm sure everything is cleaned out then I'll worry about dicking around with the carb.  Rebuilt a 4.3 throttle body about 15 years ago and that's the extent of my work on engine top ends.  

Did you check for proper timing?

Borrowing a timing light Saturday and setting it after I put the new distributor cap on.

SKIP THE SEAFOAM!!!! Seafoam is nothing but naptha, (yes the same thing they clean your clothes with at the drycleaners) It will eat the gaskets out of your carb from the inside out. I know someone will chime in here and tell me i'm full of it, but I talk from 30yrs exp. as a ASE cert master tech. Chances are you have a bunch of water in the fuel as ethanol is a water sponge, it just attracts it and will cause white rust in cast parts such as your carb. Pull the carb, get a rebuild kit and tear into it. Pay special attn. to the passage ways in the carb body and the jets. When you get it done, turn the idle mixture screws in all the way and then back each one out 2 turns. Start it up and adjust each screw in and out until you feel and hear the motor stumble a bit and adjust the screw right in between the stumble point, then set your idle speed. Should be good to go then.

Well.....

New plugs, wires, and new HEI dist cap.  Installed old coil onto cap as it looked to be in decent shape.    Drained out the last couple gallons of old gas and put in five gallons of Premium and threw in some ethanol shield and some sea foam.

Started engine, choke all the way open.  Turned up idle until it would run with choke off, then reduced idle until it started to sputter, then turned it up a quarter turn.  Took it for a drive down the mountain and back, kept it under 35 mph (my tires are in pretty bad shape).  Blew out a bunch of carbon and smoke when I first started it up, but no smoke now that it's idling good.

I'm sure the carb could use new gaskets, etc, but it didn't change speed when I sprayed carb cleaner around the outside.  Gonna set the timing when my neighbor gets home from work (borrowing his timing light), and then changing the oil and flushing/changing oil in my transfer case.

Removed bumperettes and tow shackles from rear bumper, stripping and painting it then mounting everything back with grade eight bolts and hardware.  Bought two LED deuce tail lights and fabricated new bumper extension brackets for them.  Probably wait until I order military OD paint from Gillespie before mounting them, don't want to bolt everything together until final paint.  

Hard top has a lot of rust where it was welded to the windshield and rear of cab.  Soft top hardware and bows are all intact under the hard top, so I need to figure out how to chop off the hard top without damaging them.  Ordering STA Buckshot tires and canvas top this week.  Selectro hubs arrived today, more work!