Well... Productive day today. I got the exhaust bolted up. Put fresh oil in it. Put another almost gallon of ATF in it. Got the timing set, road tested him, and checked for leaks.
I traded three batteries and $20 of AutoZone rewards to get a Marine Deep-Cycle/Starting battery for $51. The kid at the counter asked "What's this going in?" and asked if I knew it was a marine battery. When I told him that it's for a truck that I don't drive much, he had an "ahh ha" moment, and said that he'd never heard of anyone doing that before. It's got 650CCA, and like 150Ah of reserve, so it'll work for the warranty period of it, lol.
I got it started, set timing to 10-deg BDC, and then it ran a little better. Got down the road, and decided it needed more ATF, so turned around at the 1/4 mile mark, and came home, added more ATF, and tried it again. Ran perfectly, shifted perfectly, and has some nice pickup. (Pun intended.) Got it back to the house, parked it, and let it idle in D with parking brake on so I could check for leaks.
I'm going to check torque on everything, check fluid levels again, and get some fuel in it tomorrow. The gas gauge isn't broken, just the needle is broken off, and it really is almost on E.