Im just about in the 12s through 340 manifolds. Not saying manifolds are the best choice or anything, just saying you can still have some "go" until you have the cash for what you want.
What size pipes are you using? I'm debating this now. I have a 340 with 71 manifolds in a 65 b body. The right side pipe as it leaves the manifold is so flattened to clear the tie rods that I'm considering headers, the pipes are 2".