it would all fit perfectly, as the 1.6 driver bottom end is actually a 1.8 lump with different internals to bring down the CC
It should work great too, as long as you set up the idle & co properly. One thing to remember is the 1.6 flywheel will have the timing mark set to 19degrees btdc, and the digifant needs it set to 6 degrees. The Haynes manual shows you how to set the marks though. But I'd also chuck the 1.8 clutch, fly & gearbox on as well! Oh and you'll need to put the digifant dizzy on there too, and dont forget the zaust, the 1.6 zaust is far too piddly even for the 1.6!
You could just chuck the GTI head on and keep the old carb too, though you'll need to drill a hole in the back of the head for the coolant channel.
Or instead of going to all that effort, chuck another 1.8 lump in at the same time (all MK2 1.8 lumps are the same, Carb, Digi, Kjet etc)
Or even better, chuck a 2.0 2e lump in from a MK3
