going DANA 60?
Axles will cost you $300 Plus the cost of having it cut down, Moser charges $150 I think, Plus spring perches will need to be welding in the right place. For brakes You have plenty of choices, 8-3/4 and Dana 60 (with Mopar ends on the tubes) will use the same brakes. Figure $500 for disc or maybe $250 for swap meet and parts store stuff.
Or use Big Ford ends on the tubes and any ford brakes will work.
You will also need a drive shaft.
What it have for gears? Is it a limited slip ? You could easily be in over $1500 redoing a truck rear.
You can redo your 8.25 for less.
Limited slip $300
Gears $200
Rebuild kit $150
Have it installed and be done for under $1000. How often are you REALLY going to be racing it ?