it has a Holley 2brl 500cfm carb, over sized valves, 1.6 ratio roller rockers, a 274 duration .450 lift cam, dual out header going through flowmasters, and a WC T-5 tranny. That is all but i feel like i am forgetting something

 

In a nutshell, the diff will eventually blow! Find a rear from a V-8 car and you'll be fine. Did you also upgrade the front end to V-8 parts?

 

IIRC the 7.5" rear end is a C-clip design so if the axle breaks there is nothing holding the wheel to the car. According to Mr. Murphy the axle will break at the worst possible time. Get an axle designed for the power.