I agree for dollar spent besides cam these the biggest HP improvement you can do to any SB and cause they flow so well you can get away with smaller cam and make more HP than stock heads. The only real way to get CR out of a 318 is pistons, 99% of the time 302 heads are a waste of money on a straight swap no porting or milling with 318 open chamber would be lucky if you made 5hp because stock your only gonna get a .5CR bump, the only time I could see using them if you get a low mileage set for next to nothing mill and port the crap out of them to use a 268 or 274 cam on a stock short block even then a used set of magnums would be better. Fully ported 302 with big valves can't touch stock RHS.