in that case i think you are stuck with the 1.6 option only as nobody has 1776 and 1834 kits here at the moment.
in all honesty you have 3 options now:
1) build yourself a 1600 duaport, find dual carbs and slowly upgrade the performance as and when you can get parts from abroad
2) find yourself a 1800 or 2000cc VW engine (i think they are from type 4's) convert it to upright cooling (like the fan in your current engine) and use that. the only problem here is that the conversion is big. it requires a good engine to start with (good compression etc) and then you have to modify the engine bay a little so that everything will fit.
3) from time to time you can find what is called a "1700 hydraulic engine" which will give you more torque than a stock 1600 but almost all tuners abroad hate this block since it is almost impossible to modify it.
personally i think you shoudl stick with original parts and you could possibly consider fitting a turbo but first you'd have to upgrade your mounts, suspension, steering and brakes.