You would need the ends welded on STRAIGHT, which requires a special jig. The new ends would require larger axle bearings and new seals as well. Make sure the proper bearingings are available for the axles in your car. If not, you'll have to buy new axles.
The rear binders only supply around 20% of your braking. So if you're not using the brakes that hard, disks aren't really required. However, another option is getting an aftermarket kit that works with the original 'small' housing ends. I'm sure they are available. Wilwood, Bear, Aeromotive, Aerospace, etc all have a large offering.