Tough call. The ADR27A red 308 inlet manifold changed at some stage between introduction in 1976 to the end of HZ/VB. One has the barrels down the sides of the head faces (designed for water but never used), the other (later) is flat in that area. It changed at some time in 1978 I believe but not sure when. You probably need to find some very original 308 powered cars with engine numbers close to yours to tell for sure.