Yes that feature should help you and I've had the Mini Sport
Adjusta-Ride system and Gas Spax adjustable dampers fitted to my 1990
Mainstream Mini Cooper for exactly a decade now, so I can thoroughly
recommend them as top quality stuff too!
Oh and leave the plastic tops/covers on the Adjusta-Ride trumpets as
their there to keep dirt and water out of the threaded area, but you
will need a cone compressor so you can safely remove the old standard
trumpets. I believe all Mini's from 1976 onwards use the coarser
thread (thicker/wider thread on the cone compressor as it's safer) as
it matches the thread used in the actual rubber cones and it's worth
coating the actual threads on the cone compressor with grease, so it
engages more smoothly and there's less chance of cross threading.
Sometimes it's easier to do the rears first as you obviously don't need
the cone compressor there, but you can then clearly tell which threads
you need to use on the compressor anyway.
Oh and good luck with removing the old nylon cups, we had to use a blow
torch to melt & distort them to get them off.