£65 for the extended shackle kit from CPC seems a bit steep.
CPC Shackle Kit
Paddocks, and probably others too, do them much cheaper. £17.95 Front and £14.95 Rear sets + VAT makes £38.66 a couple of other bits to take you over the £50 free delivery threshhold and your quids in.
Paddocks Shackle Kit
I have a set I've been meaning to fit to my rears as my CPC 2+1 parabolics are sagging a bit after 6 years, nice and flexy though!