I would take to Kevin at Bears in Old Castle. Our side of the border. He made me a S60 for a 69 Bee a few years ago. This gives you the option to have the Best street differential ever offered in a car. Power Lock. Easy on clutches and not too tight on turns because the clutches are relaxed when not under a torque load. When the spider gears see torque, the center pin rides up ramps and compresses the crap out of the clutches, making the diff act like a spool. Locks it hard.

As for inside clearance. Depends on how you drive. The only clearance required is during articulation. The tire will travel in an arc towards the center of the car.

Stock rear ends are great for wheel clearance when using data from other cars with the same set up but if you make it a bit narrow. You can run a deeper offset rim which looks better and is a bit lighter.