302 heads for 318
I don't think the 302 head swap is worth it unless your milling and porting not much gain for the money. You'll get about .5 CR if you use the same thickness gasket as factory and from what I could find out there fairly thin 0.02?' if true a with a standard gasket you would see no increase in CR. If you mill about 0.020" off your heads you would equal the compression bump 302 heads will give you anyways and 1 CR point is said to be 4% HP increase so .5 would only be 2% which on a 200-250HP engine would be 4-6 HP which equals a $100+ per HP. So unless you get a low mileage set for free or close too it I don't think its the best swap get a set of Magnums or better yet EQ's.