Im not sure on wiring diagrams but there is a very helpful guide on here.
http://www.golfgtiforum.co.uk/index.php?topic=44637.0You say you have a 1.8 digifant 1 to KR. If your Golf is a 1990 8v gti then it would be Digifant 2.
If you have CE2 electrics in the Golf now, you need to check the engine bay loom on your KR motor, see if that is CE2 electrics aswell. Use the rubjonny fusebox guide to find out.
This guide has helped me so so much in the past. It will sort you out
I reckon you could do it pretty easy if you have most of the KR bits.
Different fuel pump setup too, as Wayne said.. I have one here from a 1.8 16v PL, same one, if you need it.
Do you have the complete and total engine from the KR? All the loom? Ecu?
It maybe a challenge but could be done. Or just sell the KR setup complete and buy a Mk3 2.0 16v Digifant 3 and fit that hehe
Good luck bud