Manifold help

I would use a manifold made for the 273/318 port size. They just flow better. Most brands have a street version that has the bosses for the A/C brackets. If this is a street car with freeway gears, I would get a dual plane for better low end torque. If this is for high revving performance use, get a single plane. Use the locating pins if the manifold has the holes or pull them out if it doesn't.