The problem with using the rear Nissan axle maybe finding gears for the front to match the rear. That 4.62 ratio (or whatever it is- I thought it was 5. something) sounds like an oddball size.
I saw some pictures last night of Currie's high pinion Ford 9 inch for a Jeep TJ. The pumkin is on the driver's side. It looks like it would work for a front swap, but it is unbelievably expensive. With disc brakes, gears, etc. it is over $3,000.00. YIKES!