Run a solid or if a Hydraulic look at some of the Hughes Grinds that have about .560 lift and ~254/258 ish @.050 duration would be about perfect. The Comp XE that is 251/257 @ .050 is a good one too but I'd look at the comparable Hughes if it were mine. 108 or 110 spread in at around 105 should be perfect.

It'll be a blast to drive, big torque and good power through the mid 5000 range, probably peak power around 5100-5200 but it really won't fall off too badly with the Maxie manifold and the right carb set up. The heads are probably your limiting factor but the manifold has a way of getting more out of them.

I'd look for about 530hp and maybe 565-ish lb/ft pretty much flat from around 2500 to 4800.

Big cubes don't really need a lot of CR (but more will make it Happier/crisper) but it will be a LOt of fun. You could put a smaller cam in it and probably grunt out close to 600 lb/ft but IMO you won't be as happy with the power curve, you almost want enough cam to take a little off the very bottom, after all you don't want it to feel like a 455 oldsmobile

The maxie ram-horn manifolds really don't give away much at all to say a 1 3/4" tube header, and they look really killer under-hood....wish I had a set!!