I'm confused here. It only cost 60 dollars to get it bored and you know it will be right. So you bought a jug that has been bored? Shops won't bore a cylinder without a piston because all pistons are slighly different in size, that's why they need it. My advice to you is to take your old cylinder to a shop and have it looked at. They will either have a piston in stock or tell you what size to order. I would not just order a piston and put it in that cylinder.