1989 3.0 Mericruser Manifold Carburetor Question

[Oklamale0236]

I’m rebuilding my 1989 3.0 Mericruser, just got the block and head and crank and cam back from machine shop. The original manifold and riser was no good. A friend had a manifold and riser that looks like it may work but my carb is slightly smaller on mounting plate. Anyone have any idea what carb I need or adapter plate? Picture is my new manifold I’m trying to use.