a buddy of mine has some what he says are E7 heads, i havent looked at them yet but i know i can get them really cheap, would it be worth it to put them on? any power gains?

 

No, basically all heads are the same except some emission crap might be moved around a little. If looking for good heads find an explorer or possibly some hi po mustangs with a 302 I think they have heads similar to the gt40. Basically any head from 72-97 are low compression heads and there will be no gains in power.

 

what if i gasket matched, polished and that kind of stuff to them?, since i can get them for probably a few buck because he is clearing out his garage

 

Porting polishing will help a little but nothing noticeable, to feel the difference you will need a better cam, intake, exhaust, etc, and port matching in a stock motor will not make a difference, the only reason to change heads is if the valves are bad or leaking or the head is cracked.

 

I ported and polished my 429 Big Block heads but I also had a cam, headers, intake and carb, you need all of the above to make it worth wile.