What Is Good Gas Mileage?

Talked to the guy last night. Got a little more information out of him. New pistons were installed in the bottom end (could not tell me if flat tops or not). Only could say that work was supposedly done to the heads (shaved, ported and polised). Did not have cam specs. Edelbrock intake. I think he said Carter 4 barrel carb. New headers. Thought that the compression was something on the order of 10.5:1. I guess I will just have to get the car started and then evaluate backwards from that point.