Icon, Diamond and others stock -12.5cc reverse dome pistons in 1.32" Compression height in various bore sizes (I'll assume you are going 4.375).

With a zero decked block (9.980) and a .040ish head gasket you can get by just fine on pump gas in the 10.8-11.2 range if you respect the ignition timing gods and keep the chambers in the 82-86cc range. Adjust to a CR you are comfortable with by using various head gasket thicknesses in your calculations.

My 400 based engine uses Diamond shelf pistons as mentioned above. Ported Edelbrock Victors yielded about 84cc chambers.

My 2 cents from doing our 511.