.. Sounds like you have quite a bit of load for a 350 engine to deal with. I'd seriously consider finding a complete SBC 400 engine with Q-Jet 4bbl. carb. It'll look just like your current engine and most things just hook right up to it. Rebuild it with KB 2-eyebrow hypereutectic flattop pistons and Summit 1102 (204/214) cam. Stock 400 heads will work fine. Gives about 350HP and 450 torque for cheap. (Or current intake and carb. will fit.) Requires the special 400" manual flywheel. Might find a 400 out of a truck with the manual flywheel already on it.