Depends on how much your budget is. The larger Astra turbo engines have been done, but you'll need the gearbox, wiring loom and ECU and it takes a lot of work.
There are SXi, GTE and GSi engines around that may make suitable donor options for you.
A fast road cam, big valve conversion, flowed head, supercharger and uprated fuel are about the best mods on the 1.6. Don't bother with an induction kit or sports exhaust, the standard ones flow really well.