13.1 compression Chev 355?
The best suggestion has already been stated. Pull one of the heads to see what type piston you have. If it is a 13.1 compression engine most likely you will have domed pistons. The part number of the piston is usually stamped on a pad on the bottom of the piston. You would have to pull the oil pan to see that number. If you don't want to buy racing fuel sell the engine. IMO more would have to be changed than just pistons to make it useable for the street.