looking for an "A" body rear end. 67 barracuda

Looking for a rear end for a 67 Barracuda. Found a couple of pieces in the housing when I took it apart. These pieces caught in the ring gear and punched a hole in the housing. not sure if I can get the hole welded up and re-use the housing or if I have to find another one. This car originally had a 6 cyl. and 3 speed manual. Rear end had 3.91 gear. Car now has 340 V8 and Automatic. Would like some better street gears as the ones that were in there seemed to make the engine rev pretty high at cruising speed. any advice would be greatly appreciated.:help: