But as the front has now been spaced out more because of the disks, has the same been done to the rear?
If not you need to need to fit the longer wheel studs and rear drums with the built in 1” spacer, as fitted to all minis from late 84-85ish onwards.the rear is still the same.
I have 3 10" cooper s wheels . Is it better to fit these?
Then you NEED to increase the track at the rear as well, and then get the tracking checked.
By fitting disks to a previously drum braked mini the front track is now somewere over an inch each side wider than the rear.
You can do this by either buying Minifins or just spacered rear drums , up to you and depending on budget.