If your a rookie or novice at this, contact a converter company for there recommendation
You can call B&M or TCI or a place that does only converters like Frank Lupo's Dynamic http://dynamicconverters.com/aboutus.htm, andthe list goes on.
I had dynamic build me a convertor for my first BB car. I sent them my dyno sheet and they built me a convertor. It was a 3900 stall. You'd never know it under normal driving. Great people to deal with.
My current car uses an Art Carr 3500 convertor. It stalls around 3300ish. Again, you'd never knwo it had a converter in it.