need 340 help

Just for what its worth. The number 1 mistake made by people that want to go fast on the street is "a great, big, cam with a single plane and huge carb". What they end up with is a gutless dog that comes to life around 5500 rpm's. Sounds like you would be happy with a high 12/low 13 second car. In my J-head 360 I use to have, I had less cam (340 cam), dual plane intake (LD 340), 3.23 gears with a 28 inch tire and a 10 inch street fighter convertor in a 3200 lb A-body and ran 13.30's all day long.
Name of the game is to have matching components. Not saying you are going to big, but don't get caught up in that "bigger is better". Steep gears, high stall converters make poor highway machines.