I had my helpers out today.  We got the motor off the stand and back in the truck in a couple hours.
New SFI certified flexplate is installed, with ARP bolts.  Motor's in and bolted up to the transmission.  Exhaust is hooked up.  

Fedex man came through today.  I got the new aluminum radiator installed, then all the accessories, belts, and cooling fan.  While I was waiting got an O2 sensor in the exhaust for an AFR gauge.  Got the carb dialed in about as well as I could with the vehicle not in gear.  I also hooked up a couple of those generic 2" mechanical gauges.  The factory gauges for oil pressure and water temp never worked that great.  I went for the $50 set of generic ones for now.

Still left on the table is hooking up the new battery cables, bolting the torque converter back to the flexplate, topping off the fluids, and taking it for a spin.

Welp, I got it back together and down on the ground.  Went for the maiden voyage.  Good news, no leaks.  Bad news, it made it around the block fine.  Then about half way up the first hill, it started running like ass and stalled out.  Very similar to how it was running the day it broke.  Except now it doesn't have a broken piston or the knocking sound.

I limped it back home and it idles fine in park and neutral.  I can rev it in park and it behaves like it should.  Its like it only shits itself when its under load.  I'm leaning towards an issue with the carb or the transmission.

I dropped on a new carb and got it tuned a bit.  Then took the truck for a drive.  This time, I made it out of the neighborhood and did a few miles around town.it shifts through all the gears.  Engine behaves right in idle and while driving.  If it keeps running like this, I'll call it a success.

Very nice, great thread OP

Love those old square bodies

Thanks you.

This square body has been modernized a bit.  700r4 transmission with OD and electronic torque converter lockup and the aftermarket AC.  It has what it takes to be a daily driver, and still simple enough to keep it on the road forever.