318 heads on a 360

This motor is already built, cam installed? Then just run it as is. I would not tear down a freshly built motor. It will have more power than that tired 318. Try the combo as is just to see how it goes, it might surprise you, then start building the tired 318. Worst case you replace the heads later on the 360, but for now run that bastard. Save those 318 heads when you replace them for you tired teener for a later build.