As title really..

Im after a pair of mechanical handbrake callipers as I dont want to take off the 4 pots I currently have

you have 4 pots on the back? seems a bit OTT, I'd be happy with drums

Look on www.marlincars.co.uk for an idea on making your 4 pots into handbrake calipers, similar thing now done by Wilwood, check the Rally Design site. Pay Marlin or cheat like me and make the bits yourself.