1) Get rid off the master and brake booster from taht bakkie and put one in from the VWpolo will need to do some modification but you need to do it.
2) i am not sure if you will be able to put bigger disc on as you will have to modify the brakets for your caliper, but get yourself a set of crossdrilled discs that will fit straigt on, if i am right your disc and hub is one piece, let me know then i will find out if i can get you a set and at what price
what engine are you running in the bakkie?
I DRIVE, I FLY, I WILL DIE. love the smell of feul, rubber and tarr