Papa, Did you do a compression test before you tore the motor down?
Is low compression why you sent the head out? Was the engine using oil previous to teardown? All of these questions bear on what you should do next. These truck engines were made of pretty tough stuff, forged steel crank, hard cast-iron blocks, replaceable valve guides, valve rotators on the truck engines, molly top rings; and the bearings are the same size as the old spray-oiler engines, that is, big and long lived. All this is to say that these engines respond well to an in-frame overhaul and if the bores aren't too worn can run a very long time. With the head off you are roughly half way there. If you have the time, do a little checking and consider doing more than the head if desirable.
The weak link in the chain, in my opinion is the valves which don't get adjusted often enough, work tight and burn. You've addressed that possibility. The next weak link is piston rings damaged by dust entering from the crankcase vent system (pre-PCV) or running without an air cleaner, which back in the day many of us would-be hot rodders discarded as unneeded junk just to hear those three Stromberg 97s howl at full throttle. Have a close look at the cylinder bores are they scratched, is the rigde at the top noticeable? While you're cleaning, scrape the carbon off the top of a piston and look for a number stamped on the piston top. If there is none it'll be a standard bore, meaning the engine has not been rebored and new pistons not installed. If there is a number, it'll be something like 020 or 040, which means the engine has been rebuilt at some time.
If the engine has been maintained with regular oil changes, etc., the crank is likely still round though maybe a couple thousandths worn. GM used to sell bearings 0.002" undersize to accommodate just such a situation. Today, you'd have to shim the bearings using tapered shim stock if you can find that. But maybe the bearings are just fine and if it's burning a little oil, a ring job would put you back on the road in fine style. A set of rings is about $100 these days and rod bearings another $60-75, mains are similarly priced and luckily for you, should you opt to change them, are pinned to the caps not the block as 1955 and earlier were.
I have been into two of these engines recently and am beginning reassembly today. Both engines were taken out of service due to a burnt piston, number 1 in one case and number 6 in the other. The bores were not damaged. The engine that came out of my truck had over two hundred thousand miles on it and the cylinder ridges just barely catch my finger nail. It had been rebored 0.040 in 1973 and had been run without an air cleaner for an unknown time before that, necessitating the .040 overbore. The crank is still round but 0.0015 worn. Were it not for the burnt piston, I'd probably have re ringed it and gone on down the road.
