I have always been under the assumption that all /6 cyl heads are interchangable with small differences in the casting, plug style, etc.
I am also familiar with the hydraulic cammed /6's that use "top down" tappet oil supply.
I have a friend who is being warned against putting a head from a hydro-cam motor on his '75 slant six. The source of this warning is normally a very trusted source (been a Chrysler mechanic and general gear-head and knowledge dome since way-way back
). As I mentioned, I thought they were all interchangeable, but I have never personally attempted a swap from an '80s model /6. I know about the funky rear rocker bolt and the different valve cover, but shouldn't one be able to put an '80s head on a '75 motor using the mechanical pushrods/rocker gear with no problems?
D/W