Just to throw this out there, I worked with a young guy years ago, with a 67 FB, with a warmed over 389, TH400, 4.10 gears, street driver. He had a 3500 stall converter, and put it in, and said after 2 weeks, he couldn't take it. Was too hard on the car. Replaced it with a 2500. I think a 10" converter might have a similar stall speed, but can't be sure. Might want to investigate further.