Now if there was a nice modern rear suspension with a monoleaf spring or coils there would be no need to worry about it
Peter,
I was talking to one of the guys from Suplex and he mentioned a GRP/Kevlar monoleaf spring possibility.
BUT unlike the front upgrde fitting rear springs isn't easy: Mike at Williams estimated 10 hours labour...so that is £800 to start. I'd guess the full job will be over £2K, perhaps near to £3K with new shocks, Panhard rod and anti tramp bars.