Billy, I started out with a 456 gear and ended up with a 355gear. You just do not need much gear with a short rod 406. Never had any heating problems. I used a 4 speed.both of the 406's I built I used 2 bolt main blocks. Many of the racers around here think the webbing is stronger than the 4 bolt in the 400.One thing I should have considered before when I was offering advice is Your chevy ll . Is it a stock frame ? Does it have frame rail connectors? Have you put a frame under it? How about suspension? Tires? Without all of this you will be quicker with a 327 or your 350. I recently sold a 63 chevy ll with stock suspension and a 355. My 406 would have been a joke in that car. One more word of advice and I'll shut up. I'd rather have a 13 second car that I can drive than an 11 second car that I can't.Good Luck and Merry Christmas!