I have had 16 GS500's so far. The 4 savages I have had pales in comparison with that ...
The GS is not as well made as the savage, and it is easy to work on, but that is mainly cos the frame of the savage is idiotic ... like exhaust pipe, foot peg carrier etc etc all fitted on the side stand and messing up the ease of taking the side covers off ...
The GS'es perimeter frame lets you do everything easy too ...
However the GS is a semi high revving motor and it comers alive past 4K or so and runs out of breath at 9.
It aint no savage ... not really torquey, they gave it cams with a lot of duration ... its revvy and not torquey.
You could do a cafe or somehting out of the older GS450 and its easily fixed up with GS500 parts if needed ... but I wont do GS motor in savage frame ... that's like throwing 2 negatives together ...

A savage motor GS500 sport single ... now you're talking. The GS annoyingly has 17 inch tires in a 130 width and chain drive ... instead it should ahve had 15 inch 150 wide rear tire and belt drive.
In fact, a DR650 motor in a GS body will be fun. As will my GR650 motor in a GS ...  

Cool.
Srinath.