There's a cost factor with the cast iron heads you may want to consider. The 906 and 915 heads do not have hardened exhaust seats for unleaded fuel. The later 452 head would require less work than the other two heads. If larger valves are installed then new exhaust seats should accompany.

The open chamber 906 or 452 head can get you a compression ratio that will help make power, but keep in mind that 9.5:1 is enough to reach your goal.
The open chamber design makes it difficult to obtain the quench most builders strive for today, and .04" quench will go a long way to deter detonation and preignition. If you're going to buy exhaust seats and stay cast iron then the 915s is the choice.

A cheap Speed Pro l2355f30 $422 from Summit can get you what you need for a few hundred dollars less than other forgings, but the other forgings are really good pistons and weight a bit less.

So, on the cheap a Speed Pro piston on stock rods with worked over 452's can get you 500hp. It'll take a thumper of a cam to compensate for the heads.

2.061 piston
6.76 rod
1.875 throw
-10.72 deck
=.021 below
.02 steel shim head gasket
88cc head
=9.6:1

Shave the heads to 80 cc and you're at 10.3:1
Put a set of Edelbrock 84cc on it and you're at 9.96:1 with .045 quench. personally I'd go straight to the TFS 240 head.

The cam will need 240 to 250 duration, minimum, depending on the head flow. The better the head the less cam required to meet the goal.
The MP 528 mechanical is cheap and it works. It's a good place to start.

The Moparts tech library has a few simple 500hp combos.