That tranny should hold up fine behind a 305. They have better gear separation than 700R4's, and can be built to take a lot of abuse if you ever decide to put something hot in front of it. Ask a Grand National or turbo T-Type owner/racer. You'll have to get an adapter however, as they are a B.O.P. bolt pattern. I think the overdrive is definately worth it though. Have fun.
