I just realized I didn't really answer your original question
Anyways, from what I understand a lot of the physical parts mount up just fine. An EJ20 swap into the GC/GM/GF chasis is fairly simple, mechanically. Takes a few hours or so to do with the right tools and knowledge. The difficult part is the wiring. That supposedly takes ~3/4 of the time.
I think it'd be a totally cool project car. I've thought about it many times myself. The route I was thinking of taking was L wagon, 2.5RS or OBS hood and front bumper (and an EJ20 swap as well). I'd say go for it.