Silly question but are 1977 2200 flexy hoses the same as on the 3500 ?
I just remembered that they did change to metric threads on the 2200 and some late 2000's, and I just confirmed that in my workshop manual. So you would need flex hoses for a late Rover 3500. The original metric hoses had two M's on them. The front hoses are both GHB138, the rear from the pipe to the caliper, is GHB303, and caliper to caliper is GHB305