Doing this I would take lowers compression slighly too, if I understand correctly. By eyebrowning you mean to angle slightly the edge up to the flame ring, outside the cylinder bore, so that fuel has nowhere to pool.
This would give you a cleaner burn I guess, power gains?
sorry it took me a while to get back, yes it will wind up lowering comrpession a smidge. but the increased efficiency due to lack of fuel pooling as well as the increased flow from the valves will easily make up for the different in compression. Our flow bench test with that lip in place show a 20 cfm decrease in flow, by eyebrowing the cylinder you pick up more flow and a better combustion event.
Jonathan