what torque converter

YOur best bet would be to spend 99$ and a make a couple dyno pulls with the car before you order.

I'd guess if you call with your specs you'll get (and be happy with) a 9.5" - 10" vert with a 3500ish stall.

Just call a reputable company and honestly give them all the info you can.

He could put all his specs through a dyno program. The more info in the better info out. It's not perfect, but it would get him close enough, IMO if he gave enough info to the program.