Is it worth putting 351 heads on a 302 in my friends 93 f150?

 

Are they better heads? Bigger valves, runners, or port work? What did they come off of? If so there could be a gain in power, but a set of conversion bolts would be needed the come with top hat type sleeves. The 351W heads have larger bolt hole than the 302 and the sleeves take-up the space. I have used them and have an old set.

 

If the heads are from the same year,and a few years earlier and later,they are the same head,so no real benefit unless something is wrong with your 302 heads.

 

From about 1978 on both motors were equipped with the exact same heads out of the factory.