BB cylinder head question

Whenever the question of what BB heads are what, I always post this link and just because it's a 67 or 68 engine you can't be sure what heads you've got (and there are differences) until you check the casting numbers. The biggest performance enhancer is if you've got the 915 or 516 closed chambered heads and still have the smaller exhaust valve they will benefit with the larger valve.

http://www.moparmusclemagazine.com/techarticles/5115_cylinder_heads/index.html