Decent Slant 6 carb, intake, header setup

I know this is an older posting, but I am getting closer to doing some changes to my 225. I would like to remove the head and have some work done. Therefore, I think it would be best to find another head to work on while I keep driving my car. I have been told that 68 or newer heads have a better chamber. Is this true? And, would any of the newer heads work with my solid lifters? Also, should I use a copper head gasket and new ARP bolts?