360 swap 1965 Barracuda

Are you sure you have an 8 1/4 rear? If the car came with a /6 it probably came with a 7 1/4 rear in it. The 7 1/4 won't take much abuse. After I put wide tires on my car with a stock 273 2 bbl. I made a hard shift into 2nd & broke the teeth off of the spider gears.