The "performer" is a descent RV manifold but don't expect it to make any top end power. It'll hit the wall at 5000-5200. The runners are smaller than the Factory 70-71 cast iron stocker which is arguably a superior piece.

The CH4B is what you should be looking at ; performance on par with the RPM and low carb height so the stock throttle & kickdown linkage will work. You will have to modify the stock linkage or go to an aftermarket (raised) bracket if you decide to use the RPM.

The CH4B will support 600HP according to the MM manifold shootout a few years back.

I had a Performer on my old 440 and wasn't impressed at all. A swap to an old school Torker was night and day difference. That 440 with a Crower HDP282 hydraulic pulled solidly to 5800 with the manifold swap. With the Performer it felt dead at 5000


Ron