What you propose is certainly possible and I've seen a few successful examples.
Couple things to think about though:
With your newfound speed and power should you have better than original brakes too?
You'll need to have axle shafts modified to the correct length and splines to accommodate the old hubs and new differential side gears.
Cutting, lining up, and welding the parts back together and keeping a reasonably straight alignment is not an insignificant task.
If there was a newer axle that solved all those concerns and even has the correct bolt pattern would you use it?? (I would)
Here's a Tech Tip about swapping too that newer axle:
http://www.stovebolt.com/techtips/bigbolts/p30swap/These axles are cheap, no one really wants them probably because of the 10 lug pattern. I'd be willing to bet you can swap the entire axle cheaper and much faster than the cut and paste method.
Grigg
