I was actually thinking of this. It does not bother me that the gasket it slightly smaller than the port on the head. I was considering even, leaving the gasket along, and making the port on the intake manifold match the gasket exactly. I would rather the intake manifold port be smaller than the cylinder head port than vice versa.
Nice project! Like the "Southern Sun" rooftop, I know it helps down there! If You cannot find a gasket that is slightly larger I would definitely trim what You have, You do not
want that gasket, esp. paper protruding into the port opening. Looking forward to how She runs, keep pluggin'!!