This is what Zippers Performance said after asking about head work on my 117:
"I have talked to my engineering department and here is what they are thinking: You are currently using the Flat Top pistons. Our CNC Head package that we offer for the 110” heads includes decking the heads to increase the compression ratio. The issue that we have with the flat pistons is the piston pocket. If we increase the valve size and deck the heads to build more compression, we do not think you will have adequate clearance in the piston pockets. You will need to do a full mock up to check the pockets for with and depth clearance on the valves. Now… I can tell you that we have a package that uses our CNC Ported heads, Zippers 12cc dome top piston and a Red Shift 657 cam, and we are making 129 HP and 121 TQ. I cannot say that you will have the same TQ in the lower RPM range as you have now, but it will be a very broad power band and a happy running motorcycle."