Ayup, I did buy a gz250 tank on the chance that it might be an easy refit to the Savage. And while it does at least have a good general shape to the bottom; by matching the split in the frame backbone somewhat; the positioning of the rubber mounts on the frame is WAY off target for the location of the corresponding mounts on the tank. So... At the very least several things will have to be changed to make a fit.
(1) The rubber mounts will have to be relocated on the frame, along with several electrical components I suspect.
(2) The rear mounting brackets on the tank need moved closer together to mate with the originals on the Savage frame.
(3) The Speedometer will have to be moved to the bars.
Some of this I anticipated, as #3 was obvious. But I was hoping to luck out on some of the other mounting hassles, but it was not to be. It isn't going to be an easy fit, and while I do still hope to use the tank on a Savage at some point, I have yet to decide exactly which bike to fit it to.
For the amount of work required to fit the GZ250 tank, it would only take slightly more work to have a 4.5 - 5 gallon tank, instead of one that isn't even a full gallon larger than the stock tank.
As far as waiting on me to pave the way for an easy solution to the problem of the Savage's tiny tank... Don't hold your breath!