9 1/4" Axle Swap?
There are several places around that sell custom length 8.75" housings. I wouldn't screw around with a 9.25 axle. They're heavy, and you'll have to get custom axle shafts. If you'll have to play with custom axles, why not get an 8.75 for a couple hundred bucks and have a choice of a ton of performance options.
Check out one of the people that can hook you up.
http://members.aol.com/doctordiff