I saw your initial posts on here when you first started and was wondering how you were doing. Holy amazing, this is what I wanted to do but never really did with a Wagon since I saw your posts. I knew the 1991-1996 G.M whales were already pretty aerodynamic for Wagons but here you've up and done all of this. Speaking for a Diesel conversion, putting a 6.2 in one of these isn't unheard of. I'm not sure what's in this car though:
If you switch to Diesel and put in a smaller fuel tank though, really... MPGs will be going into the stratosphere...