There is a chance we will be putting an F28 into an Aveo fairly soon, our 2.0L 8V making 18PSI has been eating clutches.
Surprisingly enough the original D16 is still hanging in there and that is with semi-aggressive corner acceleration.
The F28 is a big fat pig.... the newer M32 from the Astra VXR ( which I have in my garage) is a much more compact unit and it's already hydraulic and it has a cable driven shifter so it should be easy to convert ( no mechanical linkage to worry about )
If you look around the UK you might find one... migweb and ebay.co.uk are good places to start.
I imported it from the UK last year.... just haven't had the time to do much with it.... perhaps this winter I will drop it in one of my four project cars.
The M32 will be stronger, lighter and smoother than the F28.... also the F28 is not easily rebuilt since some of the internal parts are hard to find or discontinued.
In general you can still fix them.... but in some cases it means a small amount of machining to get aftermarket replacement parts from a different application to fit.
One good source for low mileage F28's is Japan.... I just recently imported an Opel Calibra AWD 2.0L Turbo ( C20LET with 4X4 F28 )
I'm going to see if I can bring in a few engines/gearboxes.... but I suppose it depends on demand.... I have to think there are only a few guys on Daewootech that would be interested in dropping the cash for a C20LET/F28