G'day cvanschreven,
If your Rover has the lifted suspension, I think the standard dampers will be too short.
I have searched my saved notes and found this message from Ben (Isuzurover)
Your info is correct. 110/RRC/D1 rear shocks will bolt straight onto the rear of a military 109". They are actually longer than OE military, but work fine, and still allow the suspension to cycle fully in both directions.
I have been using them on my 109" IIA for years. I still use the OE military Monroes on the front - reconditioned by WW shocks in QLD.
If you still have the bump stop spacer fitted you can go up to 1" longer on the front. Isuzurover
This might be a place to start for your SWB if it has the modified chassis that the Australian ones had,
Cheers Charlie