another thing to keep in mind is that most of the manifolds we can get our hands on for the older engines are/were/ designed for "wet flow" applications. I would venture to guess even the ones with efi bungs cast in them still were designed with wet flow ideals. For efi, we have to think about dry flow before the injector. You want some turbulence before the injector to start the mixing, and good velocity. But, the problem is, when you throw boosted flow velocities in the mix its tough to get all that, plus good injector targeting with the older intake openings. Just look at a modern engine and how the intake port has injector openings to help direct the flow at the back of the valve. I know on my EFI 383, you can see the clean spot on the opposite side of the intake port (bottom) from where the injector spray is hitting. Most likely at idle low flow conditions. If I could do it again, I woul look at a short tunnel ram with the injectors underneath to try and adjust that angle.