just went through your whole thread, looks great. id like to do a 4.0 swap on my 89 BII too but all i hear about from the 4.0s is about their shitty gas mileage and the 20+mpgs of my 2.9 rocks
my 4.0 got about 19 in town when the motor was fresh...
at the same time i got 26 on my first road trip. but now the b2 is running rich... idk why.. my 2.9 was ticking, smoking, leaking, and getting 12 mpgs... so..... yeah it was time for a change.
right now i get 17 in town and 19-20 on the interstate (cruise at 70)