Thanks again, guys. The guy at the trans shop says he can also get a replacement from a local converter rebuilder that he's had good luck with. I guess as long as I end up with a fresh unit that behaves like the original one did, I'm OK. Local reman unit is $150-ish, the MP P4876870AB "145k" is $200-ish, and the Hughes 24-20 is $250-ish. If they're all going to stall around 2,000-2,200 rpm like the original, the only question is quality.

For other options in the 2,000-2,200 range, it looks like the B&M, ACC, and TCI all have units in this range, too. I'll talk with the rebuilder when I deliver the trans today, and will get something sorted out for the converter before he's done with the rebuild.