Hi guys been awhile since I been on I've trying to run down parts for my car. Got a question I have a 72 cutlass supreme with a 350, I found on ebay a pair of #6 heads from a 1970 350. The bid so far is $220 plus $85 in shipping. Now is it worth it to try and get these heads or just take the ones I have on mine and get them worked on as in getting the bigger valves etc, or is there a big difference in cc and compression and valve size and how much would you guys pay for the #6 heads? Thanks again for all the help and advice!

 

There isn't any difference in chamber size or valve sizes between the two. Personally, I would spend my money on the 7A heads unless you can't have the vehicle down while the work is being done on your current heads.

 

X2

If you want higher compression you'll have to mill the heads, deck the block, replace the dished pistons with flat tops, or a combination of the above.
Don't just throw parts at it, it's a waste of money (ask me how I know). Write up a plan, starting with your desired results, and work from there.