Just to clear a few things up:
I experimented with some parts available to me. The plastic, oval port, 3.0L lower intake manifold will bolt directly up to a 2.5L cylinder head with no modifications, no hole drilling.
However, the ports in the 2.5L head do not entirely fit inside the oval shaped lower intake, i.e. it will leak bad. And as said earlier, the injector port is a problem. It is centered and situated very low on the lower intake. You would get about half the spray in the ports and the other half on the intake mounting surface.
A spacer plate would be required. Sealing the spacer plate might be a little tricky but do-able. Sounds like a good opportunity for someone to make up a conversion kit and sell it here.
