I run a small port 270 head with a 4 bbl manifold for a 302. I made adapter rings. The problem comes in sealing it to the head as the gasket surface on the head is smaller than the manifold. 270 gaskets are too small and 302s are too big. The head could be milled but that is just more trouble. Even with a 2bbl adapter you have the same size hole on the manifold. That said, I ran a 2bbl through an adapter for a while and the 207 liked it.
