After reading this:
According to the above topic Liverpool Victoria makes it feasible for an 18 year old to have the 2.0 XET 16v Turbo engine for an extra £28 in there originally 1.1 nova. I thought how about converting the G with one of these engines, but then I had a look on the Courtenay Sport website at conversions and it will be in the region of about 5k minus the engine, which is out of my price bracket, so can this be done by your average mechanic is converting the engine in the g a really big job, is it going to cause many probs and finally is it guna cost.
This is what Courteney says
An evermore popular conversion nowadays is the Engine Transplant.
Almost any GM engine will fit into almost any GM car. It's not always as simple as that, naturally, but it usually can be done.
Then, of course, there's the 2.0 XET 16v Turbo engine from the Calibra Turbo. That'll go into anything from a Nova to a Frontera (yes a Frontera!) too.
I have a copy of April addition of TV and there is a mk3 GSI and the bloke who owns it converted the engine himself to a 2.0 XET 16v Turbo engine, with some help from mates and reading it seem like he did it no sweet?
I would be inclined to have the 6 speed box converted so the g can remain a front wheel drive car.
Are the 2.0 XET 16v Turbo engines very reliable, would it make life easier if I could get hold of an engine and gear box wiring etc out of maybe a smashed up Astra coupe turbo. Would I find a new engine used in the coupes very easily and for reasonable money?
Any advice appreciated?