A 700-R4, if properly set up and in good condition will work. I'm putting one in a 440+ hp '34 coupe, and the one in my '93 Vette (300+ hp) works just fine. You may want to beef it up, however. The stock converter may not be right for your engine either.

You might want to do some reading here:

http://www.bowtieoverdrives.com/index.shtml