The changeover for Chev was in 1987 so you SHOULD be fine, I think. The newer heads are for centerbolt valve covers and had a higher side so that the oil did not rest against the valve cover gaskets and eventually leak out. The bolt holes were different after they did the change in 1987. Basically if you have a SBC then its pre 87 or post 87, the once piece rear seal was another change. Your newer intake should fit on the heads fine.

The vortec style heads are also what you have to watch out for...the intakes are different.