Well I've eventually got round to it. New rear leaf springs cos one had snapped halfway round the rear eye!
New extended shackles and a front torsion wind up.
Could not have done it without use of my friendly mechanic's tools and ramp (and help :D)
This was a bit of a pain to do as the drivers side spring needed cutting out with the oxy-acetyline torch due to corroded bolts.
I am very pleased with the results, 3" lift at the back (which should settle to 2" as springs bed in). Plenty of clearance for the 235/75 ATs and looks great.
I am amazed by how much better it rides, the old springs and bushes were well shagged!
FYI - leafs springs are 2+1's made by SMJ products in Leeds, excellent quality for Ã‚Â£160 for the pair. Shackles were fabbed up by a local engineering firm (also 4x4 owners so did a good job).