The 308 heads are marginally better in STOCK form than the early heads. Now for the bad news,they are cracked or will shortly,so do you want to put the time and effort into them? I port my own so if I have a head crack it's not a big loss.Same goes for spending $$$ on the magnum heads,I'm not suggesting that a good valve job and minor porting won't help them. As far as the MP porting templates,I own a set for the magnum heads,funny how well they fit the stock magnum R/T heads.