Homemade intakes are a little tricky. I built one a number of years ago, but fixing leaks was a real issue. There are so many places to have leaks, porous welds, flanges at the head, flanges at the carb/throttle body, etc.
The new 12 port heads look awesome. Obviously, with a turbo 750 holley, you are after power and performance. My goal is maximum fuel economy. I think those new heads would be great for either. If opt for one, you may find yourself fabricating another intake manifold. I found a way to quickly isolate leaks at the welds. I have a friend who owns and operates an auto repair shop. He has a smoke machine he uses for isolating leaks of any kind. I used it on the last couple of headers I built. Just feed the smoke (under mild pressure) into one port, and plug all the other exits. If there is a pin-hole anywhere, the smoke will stream out. Easy to see. Then the only concern is getting true mating surfaces.
