There is that, but its a lot of work when you already have the injection system fitted. Main issue is the lack of a lambda hole in the oem downpipe, once thats sorted its not too bad providing you have a CE2 fusebox. Then again even if you have CE1 its not may wires to splice to get it going!
All assuming you manage to get an ABF with all the loom and ECU, a complete donor car makes more sence if you plan to go that way, or at least take someone along who knows exactly what you need. Forgetting things liek the airbox, transponder ring if its a post95 with immobilisor and other little bits n bobs will make for frustration later on down the line.
Main thing to think about when you make this descision is how long you want the car out of action and how good you are at wiring. I've driven my mates ABF on the MK3 managment and my own on KJet, the k-jet feels more 'urgent' for lack of a better word.
The ABF managment is more refined, it doesnt feel as fast but it definitly is! flat out in my MK2 2.0 8v I couldnt keep up with him and he wasnt really trying
The other reason for runnign the digi setup is its got more scope for tuning, plus not so many places can deal with the old Kjet system its starting to get a bit specialised. A big plus is you dont have to mess about playing with idle n co screws, or use a timing light to setup the ignition it all takes care of itself!
Edit: getting a VAG-COM cable is a must, diagnostics on these saves a lot of head scratching if things dont work as they should!