Dragula...the intake he has looks just like the Barton single plane, it's just a 4150 flange. Sold as a MP part and has "MOPAR" cast where the typical Barton logo would be.
You should be able to redo the flange on this manifold for the 4500 pattern. It's shorter than the Barton manifold and I have seen the Barton manifold cut down to fit under the hood.

Cape...hemis can tolerate a lot of compression w/ pump gas. There's a few around 12:1 doing it. I'd try a thick head gasket and get a custom cam ground for it. Call Dwayne Porter for a cam. 802-951-1955