always put a new converter in with a rebuilt tranny
that said, the stock one for our trucks stall at 1428, you can get stock replacement converters at 1211, 1428, 1568, 1639, and 1996 stall. i have the 1639 in my truck and it pulls well, thinking on going to the 1996 next time.
the 1639 is a 5.0 4.3 5.0 IROC converter, the 1996 is a 5.7 corvette, 5.7 police, 5.0 MPFI IROC converter. those are the only applications that i know of.