The 302 ports are almost identical to the older open chamber versions. The major difference is in the combustion chamber. It has a squish pad that looks similar to the older 273 heads; except the 302s squish pad is heart shaped, and the 273 squish pad is more squared off. Anything you've learned about the older 318 heads pretty much apply to the 302's as far as larger ports/valves etc.
As for availability, they were introduced mid-year 1987 (I seem to recall) and ran to the end of LA 318 production, 1991. I have a set in the garage from my dad's '90 Ramcharger.
