If any one finds a 'trusted' garage please let us know, I could write a (very long) book on the bad ones ! When set up properly the brakes work very well. It could be that with discs on the rear they would lock up too soon and would need a release valve, or something. George.
Not really likely George. Discs aren't self energizing like drum brakes and really require a larger brake booster for higher line pressure. As long as the caliper piston ratios are taken into account there won't be an issue. Mirror the caliper sizes/brake system front and rear to the Factory design of a similar sized vehicle.
The Jaguar MK2 rear caliper assembly can be adapted to the Rover differential. The Jaguar handbrake mechanism will also hook-up to the original Rover assembly. The length of the Rover handbrake cross link arms at the rear needs to be lengthened byabout 1" to increase the mechanical ratio of the handbrake mechanism with the rear discs. The original front discs can be retained. Upgraded drilled and slotted discs can be substituted for the solid originals.
If you're in OZ a 1980s Ford Falcon diff (vented rotors, lower ratio differential gear set, LSD) will fit. A Rover club member in OZ did this conversion many years ago. He used the Ford stud pattern front and rear and fitting modern alloy wheels. He also drove the car from the East to the West coast of OZ and back. No mean feat!