The girdle and aluminum main caps aren't required for the power you said you wanted. But then you added another post about nitrous so maybe you'll be making more power. It doesn't seem like a nitrous cam so I'm not really sure which way you're going. Are you working with an engine builder or are you planning to bolt it together yourself? A lot of engine builders won't touch the girdle and aluminum main caps but maybe you have one who is okay with that kind of stuff. I've built a lot of Mopar race engines and I've never used a girdle or aluminum main caps in any of them. I used to try a bunch of "trick" stuff but these days I build them fairly simple and they seem to work better.
Are the heads ported or out of the box? I assume those are Victor heads? If so, you'll want to work with an engine build who has some experience with the Victor heads. I'm not a fan of them myself but there are guys around who have figured out how to make them work. Brian at IMM is in SoCal and he could help you with the build if you don't have an engine builder.