Port my current M1 single plane or install the RPM Air Gap?

Nice build. Normally I’d say a cam @238@050 is small for a single plane but up top a 408….. I’m betting the engine will like it.
Most runners on the single planes are undersized and after porting to meet the head, both of which are typically ported to the gasket size, will wake up and make good use of a single plane.

Personally haven’t been there. Hopefully correcting that soon.