Best value for money is just to drop in a later model 1800 or 2.0 Litre.
The going price for a second hand 180 from a MK3 Golf or Seat Cordoba is about $450.
Most people wouldn't even consider doing anything to the 1600 but they can be made to go very well.
Have a look around the forums , there's heaps of info on what motors fit in the Mk 1.
Pete
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