I have a question for you. What type of gas do you plan on using in this rat rod. I see you have a problem. You are going to use Vortec heads which are 64cc chamber heads. In your short block measure the distance from the top of the block to the top of the piston at TDC. You probably will have .025. This area from the bottom of the head to the top of the piston at TDC is call Quench. The recommended Quench is .040. So if you have .025 you will need a .015 head gasket. This setup will give you around 10.425 compression ratio which is too high for pump gas. If you use a .040 thick head gasket to bring the compression down the engine probably will ping under load. You need to talk to your machinist and motor assembler. The 12cc dish piston should have been recommended for using Vortec heads.