The 2.02 valves being a problem like requiring bore notching and such on a 318 is something that was started many many years ago and simply is not true. As I have run 2.02 valves many times in several different 318's with no issues. Think about it all 318 340 360 LA heads have the exact same valve spacing add 2.02 intake size and 1.60 exhaust size together that is 3.620 and a 318 stock bore size is 3.910 there is no where near .290 separation between the intake and exhaust valves on any of these heads it would probably be a issue using 2.02 valves on a 273 but it never has been on a 318 and I don't see valve shrouding being a issue neither all the 2.02 valve heads I have put on a 318 have always made a major difference in power as long as you deck the head or block to keep the compression from dropping I have used new pistons many times though with valve reliefs in them because you cant run much cam with 318 stock flat tops with no valve reliefs cut in them. My