Narrowing an 8 1/4" rear end, how is it done?

OK, not the greatest title, but whatever.

My '67 Barracuda has a GM 8.2 rear end on it, for who knows what reason. I found a 8 1/4" 3.21 4.5" bolt pattern open rear end that's already had the perches moved for an A-body. Problem is it's supposedly 63" flange to flange, but the guy didn't get around to narrowing it because he found a 8 3/4". The price is too good to pass up. I've never narrowed a rear end, but I do know the axle tubes and axles will need to be shortened. Are the axle tubes something a typical driveshaft shop would do? As far as the axles themselves, shorten them (if it's doable)? Or am I better off looking for a set of new or used axles?

This is going behind an A833 trans with a 360 Magnum engine. No outrageous HP :)