easiest way to go about it would be find a 61 [or that series anyway] at a wreckers that had a V8 and scoop the mounts and anything else that's different tween 6 and 8 - for good mileage, keep it well tuned and keep yer foot outta the carb!
not sure about the rear gears, as w/ 4x4 I understand ya gotta have the right ratios front and rear [same?]
Bill
