I'm not sure on the paint, but have a buddy that does autobody and restoration work and can ask if really interested. Most likely you already have 906 heads unless someone changed them and they flow fine. The 452s will flow the same but have the factory hardened seats already. We've built many strong motors with both of those heads. But to compare, the aluminum heads will flow better and you can run higher compression. I'd think for a bit & come up with an idea and plan of how you want the car to perform and let us know. There's a wealth of knowledge here that can help you get there. It might not even require purchasing as much as you initially believed.