Obviously, the suspension issues is the wild card as far as $ is concerned. KB hyper pistons would be a better match to the rest of your rotating assembly and save you a few more $. Think they would live just fine on premium pump gas with that CR and aluminum heads. Carbs too small IMO. Maybe a 800 / 850 cfm. I have had real good luck with rockers from Hughes - (don't know who makes them for Hughes) and they have a large selection of Hydraulic cams to choose from.. Don't know anything about those heads, but it is always less expensive to by turn key verses bare, and at 500HP I'm sure you could by off the shelf complete heads that would work. Buy them complete, pocket port them yourself, and you should easily be able to make your goal. 500 HP is a nice safe realistic # for that block. I'm sure you realize that if you want more HP in the future you gotta start from scratch over again. Plenty of people on this sight that will remind you of that - and they got no problem at all spending you $. You now probably have enough $ left over to buy a complete after market K member.