A "vette" TH700r4 converter is the same as the "IROC" and the "S-10" converter.
the stall is a bit higher 2200 rpm behind a 350. I had this converter in my th700r4.
(when I switched to a th-350 and 3600 stall it picked up 4.5 10th's)
There is a 4 letter ID code on these GM converters. I forget the code.
For the th700r4 a real deal 9"-10" 245MM true high perf high stall is the way to go.
The smaller converter is much much better.
If you want quick, get agressive with the the stall speed and gears even with a "268"
3500 is not too much at all. Most people wimp out and waste their money.
a 292H needs a 4000+ lock up.