Need help on heads..302

[SLEEEPER]

I am helping my brother rebuild a ford 302 from a 74 falcon. the block and pistonsd are on very good condition but no heads were included in the purchase. Not being familiar with head #'s. Are there any particular heads to keep an eyey open for. I co to a wrecking yard often for parts and would like to be able to ID a good set of heads.The cam he wants to keep stock. (so far) but better heads than stock if we decide to update at a later time. We are going to build the heads ourselves and farm out the machine work.
What years are better than others ,if any?
will 351 neads fit? Gains or losses going with such a adaptation. easy on me. I am a newbie.