I don't have "the" answer for you, but can give you something to think about. My RB 452 has less compression (11.5) and standard ports, but comparable flow #s. Dwayne Porter spec'd a 265 at .050 x .650" on 108 LSA solid roller, which made peak torque at 5100 and peak HP at 6900. Your MW ports would probably push the peak torque & HP RPMs up 300-400 over mine.

I don't recall what you may have for converter stall or what RPM you're willing to spin your engine, but you may be able to better predict what size cam suits your combination based on this.