We just finished up one of these builds a while back on the same model bike. I would recommend sending the heads to John Sachs. With mild work, he can really pick up the flow on those for you. I let him drive on the build and did what he requested except what the customer did not want to do which was change the oil pan to a later model pan and to run an X pipe. Customer already had Rinehart true duals and did not want to spend the extra coin there for the few more ponies it would have probably made. We bored the stock cylinders and installed the Wiseco 106 flat tops as Sachs proposed and picked up a Kuryakyn 57mm Wild Things throttle body. That being said, S&S makes great products and we have some killer deals on S&S products right now. No reason to fear a forged piston. Just let the bike warm up a little before just railing on it. If they are fitted properly, you will be fine if everything is clean and assembled properly and the engine is happy with the fuel and timing and break in is done properly. BTW, S&S now offers their cylinder and piston kits with CP pistons as well, FWIW.