I just barreled an upper with a custom headspaced barrel and chambered a 223 rem round.It chambered but was hard to extract,requiring a very hard pull on the CH.Safe to fire?  Should I try to find a bolt that headspaces better or will it wear in?Finish ream?  Carry it to my nearest gunsmith?

Bladework
A headspace gauge is a modest investment and is worthwhile if you plan to do much of this.  If it closes on a go gauge you should have no problem.  

If the barrel or chamber is chrome lined it should not be reamed out or opened up.

Headspace is only one of many diminsions of a chamber.

Look at the bullet.

Do you see land marks on it?

When you ask for a "tight" head space chamber what you're really asking for, and what the barrel smith hears, is a short throated chamber.  It may or may not be problematic.  You should at the very least re-seat the bullets deeper until they just touch the lands and fire a couple rounds and see if you have any high pressure signs on your brass (shinny ring around the base, loose primers or pierced).  Gradually decrease the amount you set them back until they are back where you started from, checking for high pressure along the way.  If you see no signs you may be ok with that ammo.

Another problem you may run into is that once a round is loaded you almost have to fire it.  The bullet is being forced into the lands and if you keep ejecting it as a loaded round one of the times you might just end up pulling the case off the bullet, dumping a bunch of unburned powder down into your lower and a bullet stuck in the chamber.  

Barrels like this are for the experienced reloader.

As much as it pains me to do so, I gotta agree with Halfcocked.  [:D]

Bladewurk, it sounds to me that you got exactly what you asked for - a steel barrel with a tight chamber.  What you have now is an AR that will probably work ok if you want to carefully handload each round, and spend more time developing loads, cleaning, and futzing with your rifle then you do actually shooting it.  If that's what you like to do, then great.  On the other hand, if you're idea of fun is buying cheap ammo at gun shows, taking your AR out to the range, and blasting several magazines through it without a hitch, better leave this rifle at home.

My favorite FrankenAR is a 14.5" M4gery I built on an Olympic lower, no-name upper, with the rest of the parts of questionable origin and quality bought cheap at gun shows.  But the barrel and bolt are genuine Colt.  That rifle has never malfunctioned, ever, gobbles up any cruddy ammo I feed it, and out shoots my buddy's factory Colt H-BAR at 600 M with surplus C-77 ammo.

It's your choice.  If it was me, I'd dump the "Match" barrel, replace with a mil-spec chrome-lined tube, and go shooting!

I don't know what the whole story is here, did you order it this way?  Did you plan on reloading?  Are you trying for the mythical, 1 hole after 10 rounds at 600 yards, rifle?

If it isn't chrome lined you could have the throat re-reamed a little deeper.  If you want to chase after the 1 hole thing take up reloading.  If you want something something half way between Homo's no worry, pretty accurate M4 and the mythical one hole'er, buy a box of 69 grain (depending on twist rate) Gold Medal Match and take them, with your barrel, to your barrel smith and have it reamed so that the bullet is 3-5 thousandths off the lands.  That is the way most reloaders would load this bullet.  You will also be able to shoot most other lighter factory ammo with out too many problems.  

There are some other bullets, VLDs, that actually shoot more accurate when seated into the lands, yes 3-5 thousandths into the lands, but you have to work up your loads from way under what is normally listed as max or even medium because this will cause higher pressures.  A common way to find this load is start at the minimum and add .1 grain up to close to the max.  Shoot the lightest loaded first and work your way up to the hottest, stopping when you start to see high presure signs.  Mark each hole with what number and loading it corresponds to.  You will see a verticle dispersion from slowest MV to highest MV but there will also be a group some where in the string that will mark your "sweet spot".  This is the load for that bullet/brass/primer/rifle combination.  Do this from a bench shooting at 300 yards or better with a good scope and target made for cross hairs.

Then start working on how much into the lands.

Then start all over with a different burn rate propellant.

....different weight/style bullet.

...brass.

....etc, etc, etc.