I bought a bbc that has a 2 carb tunnel ram and I want to switch to a single plane intake with a 1150 carb. It is a 4.380 bore x 4" stroke with BB2 plus heads. The heads are CNCed at the valve seat and at the intake port match so does that make these the CNCd version? But I need to know which intake to get for these heads. I can do the basic port match and smooth out the plenum area witch intake will work for this set up and take the least amount of work. And when do I change out the o-ring wire in the block, every build or when? Thanks guys.