Wayne:

I'm not sure what the exact part was that cured the not start when hot problem. Since the parts were cheap I replaced the coil & plug wires, distributor cap, rotor, that little clip that goes on the dist. shaft & rotor (what the hell is that about? Oh, and the replacement part I bought from YT was junk, it broke when I tried squeezing it to make it tighter. Fortunately the old one was still good so it went back in.)

I also removed the starter & cleaned where it & the flywheel cover where they mated, & between the flywheel cover & the block. I replaced both terminal ends on the battery cables. I removed the ground cable & cleaned it & where it grounded to the frame. (The whole time my buddy kept saying it'd ground through the bolts & I kept saying not always. When I cranked it the engine spun over faster than it ever had. I grinned & he looked down & mumbled.)

Back to the current problem: The coolant had been in the tractor for at least 13 years & it was still bright green. Normally when a lot of sediment builds up in a block it is rust & colors the fluid orange. That & how easily it flowed when I put a hose to the block makes me think there's not much, if any, sediment in the block.
The V belt driving the power steering pump needs replaced & it was kinda loose. The one driving the generator was a bit tighter, but both will be replaced. Hopefully, that will be the problem, but since it had two belts driving the water pump, I'm not so sure.

Thanks for the info about setting the timing w/o a light. I suppose the flyweights in the dist. are fixed so the timing advance is set by design.

I guess what I'll do next is replace the V belts (making sure they're tight), put it back together (leaving out the thermostat) & getting a test kit to see if the head gasket is leaking.
If that's the case it'll take him several months to save up enough to have the head milled, valves replaced, seats reground & a new head gasket. (He's on disability & won't want to do all that, but I won't not do all that; the valve springs are 60 years old.)

Any idea how much that'll cost?