non of the MK2 stuff will work on a MK1, mk2 under car pump is too big and lift pump wont fit in the tank.
what you need is a MK1 injection under car pump, accumulator & lines, plus associated brackets. make sure its from a k-jet model as very last cabby models were digifant. The last link there looks to be the correct fuel pump, just need the lines & accumulator + brackets to match.
Then you have 2 choices:
1. replace fuel tank for MK1 tintop GTI item
2. fit later MK1 cabby/scirocco lift pump, reservoir and lines to the pump into your carby tank