found some X heads

All 340/360 heads up to the release of the 308 head have the same flow potential. They all have the same port shape and size and only whether they have 2.02 or 1.88 valves will impact the flow.

If you already have a set of 360 heads invest your $300 in them. Also, 2.02" intake valves are only going to help power in the high rpm range above 6000 rpm. If your car is primarily a street motor you would be better off with the 1.88" valves.