A good starting point is to ditch the standard carb and fit the weber upgrade, G&S sell them.
Just fitted one to my 1.8, WOW, what a difference.
You will have to fit a choke cable though, the weber is manual choke.
Well worth the hassle though.
You could also fit a mk1 gti exhaust manifold and system, help her breath more easily.
Fitting injection is a chore as you will need wiring, pumps tank etc.
Fit the weber and enjoy.

Woody~K