interesting little car you have there, quite rare!
there isnt anything engine/fuel/gearbox wise you can use from the 1.3, its all different so you'll need everything from a donour car.
You'll need a gearbox from a GTI of some kind, and you match the clutch kit to the gearbox

You'll need a flywheel from a GTI as well, plus you'll have to think about what you're going to do about fuel & ignition, if you have a donour car the same year as yours you can just swap everything off it (hazard switch on dash = pre-90 spec, hazard on column = 90 spec)
Carbs would be easy, you just need to hook up an accumulator and leave the old 1.3 pump in, this should supply more than enough. It wont be man enough for injection though, so if you go that route you'll need the in-tank & main pumps, fuel lines, injectors etc.