I assume that since the LT4 head has a raised port and larger intake runners (195cc) that the intake itself has larger ports to match the heads and required intake flow. Is there any truth to this and if so, is there any advantage to port matching a set of mildly built LT1 heads to an LT4 intake? I'm talking about raising the port and tapering it into the head a half inch or so. Nothing crazy. It would actually be on a 383, 11 to 1 with the XE 224/230 cam, and other stuff in my sig.

 

First, there is an interference between the LT4 intake and the valve cover rails of the LT1 heads that requires machining one of them for a correct fit.

Second, your assumption that the LT4 intake has raised runners is incorrect. While the LT4 heads have the 0.100" taller runners, the LT4 intake ports are virtually identical to the LT1 intake ports - apparently GM ran out of $$$ while developing the LT4. The LT4 intake does have more meat on the top of the ports, that can (and must) be removed to allow the LT4 intake to correctly support high flowing LT4 heads.