Fuel efficient cherokee

I am redoing a 1983 Jeep Cherokee to use as a daily driver.  I like the body style and the idea of driving something other than the run of the mill SUV.  I will only be using the 4 wheel drive for possible snow and off-roading when I’m tracking down fishing spots.  My main goal over all is the fuel economy and not the off-roading.  I have 3.07 gears, both front and rear in Dana 44’s.  I want to replace my engine transmission and transfer case with a Chevy setup out of a newer model 4x4 for the better fuel economy.  I know that I want ether a 5.7 or 5.3 V8 with a 6 speed automatic transmission (6L80).  I hope to be able to use readily available modern programmers to help get the best MPG possible. Here are my questions.

1. Should I put lower gears in the front for better traction?
2. Would that affect the MPG or not since it spins free unless engaged?
3. Is there a better setup for MPG then the V8 and 6 speed auto?
4. V6 uses less gas but would it be a dog with the Jeep at 5000lb?

I know these aren’t you normal “How can I make it bigger and badder” questions, but I have muscle cars for that.  This is just a cruiser with 4 wheel drive.