What rear-ends and Transmission can be either bolted in or easily adapted (kits or otherwise) to a 63 Nova 2dr?

The current engine is a 350hp 350 with a Turbo 350 auto and a 10 bolt differential.

I would like to swap in a 5 speed and a 12 bolt but don't want to have to butcher the car to do it or spend big bucks narrowing the rear end etc. Minor cutting/welding is OK as are adapter kits/X-members type stuff.