Ron, your 850 will outflow the HP950. There's a thread elsewhere in the Race section on a 4150-style 1050main body, which I'm thinking about for my Duster. Last comparison test I saw, think it was by AndyF, IIRC the crossram made less power than a good single-plane single 4bbl; someone correct me if I'm wrong. Crossram definitely scores on appearance, though. I'd still like to know the cam & rocker specs.