It sounds like you have put some money and thought into this motor. The guys are correct on checking the clearance. Your .020 is to big a gap. In my opinion,most clearances are checked at or near the center of the cylinder.See what the manufactures of the pistons say about where to check clearance.You are right to question this. Track it down, and be sure.
Good luck, and let us know how it turns out. will ya?
Slider in Wa.