Merc EFI with oval port heads
 

What application/year 454 would have came with oval port heads and the
mercruiser MPI fuel injections(the one with a two piece manifold)?
reason being, I have the lower base manifold that fits the oval ports
heads, but i need the matching upper plenum. The upper plenum from a
rectangular port engine would not fit. If anyone has that part number
that would help me greatly.

Merc EFI with oval port heads
 

Ok, so i found out what i have is an HP500 lower manifold. So new
question, did any merc 454's come with oval ports and MPFI?