For american built engines.
From what I have read and seen, the casting marks, 4V, on the heads mean they are american 4v heads. If there are no markings then they are 2v.
For aussie built engines, a 4v engine came with a 4 barrel mainfold and carb, and the 2v was a 2 barrel manifold and carb.
Anyone else know if I'm right?? (Don't mind being proven wrong).