It's amazing what you can do if you've got a big enough hammer
We had a quick measure up of the bottom chassis rails on Chris's car "empty" before we started and found that the back was about 10mm lower than the front and the driver's side was about 10mm lower than the passenger side. This lean was confirmed with a spirit level across the roll bar.
There are tank trap sized speed bumps on the way to Chris's house so we knew the car had got to go up about an inch to stand any chance of getting over them. Removing the top mounts for the rear springs we re-drilled them to lift the passenger side 20mm (ish) and the driver's side about 30mm (ish). Somehow or other we managed to get this right fist time !
We then wound up the coil-overs at the front, lifting the driver's side by about 20mm and the passenger side a bit less. We then checked the weights on the front wheels and adjusted the passenger side to get it correct within a few kg.
When we'd finished the driver's side was about 5mm high "empty" and 5mm low with Chris in the seat (near enough I reckon), the rear is now about 10mm higher than the front and the car has the typical 2B stance with a fist sized gap between the rear wheels and arches. The plan is to clock up a few miles in it now and see how it goes before deciding if anything else needs doing.
Total cost was 3/5 of nothing much and a few hours of micky taking - it would have been a lot quicker if I hadn't wasted a good couple of hours trying to stop Chris humming the theme tune to Raiders of the Lost Ark however, he was very good a fetching all the bits that I managed to keep dropping into the pit