Ideally you should have started with a stock one, but right now you've got what you've got, and it might be pretty hard getting your money out of it.
Like others have said, however, it should be fixable, first get your tire swap deal. Get the springs back under the axle (hopefully they did not destroy the original pads).
The 4 cyl has an electric fuel pump (unlike the mechanical pump on the i6) so the likelihood that a lot of gas has gotten into the oil is pretty low, but change all your fluids
You're gonna have to put some good money after bad, but it seems to have a good body and on a Jeep that means a lot.
BTW I understand your decision, I came out of an Acura into my YJ 6 years ago. It's now my daily driver, off road toy and road trip vehicle.
'89 Wrangler YJ
97 Grand Cherokee (ZJ)
87 MB 560SL roadster