i've been speaking to a guy about some head work and he said he can port and flow me a head and also for no extra charge, cut in bigger valves(not supply). i need to know if a set of 1600 valves will fit in a 1.4/1.2 head, presuming the seats have been cut to fit. is the valve head the only difference? as far as i know the stems and guides are the same, is this right?