Pitted Seat and chamber

You gonna be towing with that car? I'm not so sure you're going to need hardened seats. I've torn engines down a lot and about the only times I ever saw seats needing replaced was when the guides were worn out. A bodies are light and yours is going to be powered with a hot small block. Not much resistance there and exhaust temperatures will probably be pretty low. If the rest of the seats are in good condition, I would try to clean them up and go. JMO.