8 3/4 gears

Anyone know where I can get a 2:76 set of gears for an 83/4 rear with a 489 case?
I swapped a 5.7 with the auto transmission and all the computers from an 07 Charger into my 70 GTX. My goal is to get it as close to stock as I can and once it is running I will mess with it.
The gear in the 07 was a 2:82 so a 2:76 would be an almost negligible difference