Thanks drg84, I considered keeping the original 324 Rocket engine but the availability of performance parts is almost none. You can replace almost everything with nearly stock parts from Kanter. I'm looking for more torque too.

The original hydramatic is in pretty bad shape too. You are right though about the bell housing, you need a conversion built up to use any newer tranny on a 55 olds motor.

I am going to map out the engine bay just like you said. There is still a lot of room in there but it may affect my choice of intake manifold, carb, and air cleaner if it is much taller. As far as length I am prepared to move the whole radiator assembly forward a few inches. There is a few inches of room to play with length-wise if need be, it'll take some creativity though.