Stupid 3rd gen section, tricks me all the time.
Everything I said is valid for a truck with a stock gear-drive case (ie, 1st gens with the W56). With your R150, you would need at a minimum to buy an adapter to tie your transmission to a gear drive case that you could install the 4.7s in. Or, as Whitey noted, go for a solution like a Lefty or Tacobox, which I don't know enough about to comment intelligently on. If you're looking for options, call the guys at Marlin Crawler and Advance Adapters and see what they've got for you.
For my setup, high range first gear is almost identical to low range fifth gear. Check out Gear Ratio Calculator if you wanna play with the numbers.
Damn, so it isn't so easy for us 3rd gen guys. And I'm too cheap to regear my diffs, never mind installing a dual t-case setup. I guess I'll be sticking with my 265/75/16's and stock diff and transfer case gearing...