apologies for a slightly late reply, was waiting for it to stop raining
I hope this is the correct measurement for you Bob.............
I,ve measured the ride height with all 4 wheels on the ground, then jacked it up, removed wheel & the brake drum, then lowered the car & putting compression on the rear upright / suspension to the original ride height.........so as to get as close as I could to the measurement you need.
from the face of the hub( where the studs are
) to the GRP of the rear tub under the wheel arch is 205mm.
Sorry for the long winded reply but wanted to explain how I got that measurement so you could possibly work from that etc.
HTH
cheers
andy