Building my first 8.25 rear..
You need a different carrier also to run 2.73's and up.
If you going to set the gears up you should try to find a 2.73 gear and carrier Junkyards, should be cheap, $50--$75 if the place is fair. If they have any mopars out there, lots of 4 door cars had 8 1/4 rears.
With 2.45 the engine is going to lug most of the time. If you hardly ever floor it work ok, you might get 20 mpg on the freeways but 2.73's will be close and feel a little better. Won't hurt to look around, ebay also but then there is shipping costs, too much.