I sell peanut AND coffin tanks for $99.95 USD. Plus tax and shipping. They are 2 or 2.5 US gallons (approx). You'd have to minimally mod your frame's backbone to run ANY aftermarket chopper tank, 99.99% are made to fit ROUND backbones, the Savage unit is square. They take HD MANUAL fuel valves, not the vacuum junk. And mount with bolts THROUGH the frame, not silly little rubber blocks.
I haven't measured them yet, but they look like they'd fit okay. Speedometer would have to be deleted or relocated. If there is any interest, I don't mind pricing a tank/petc0ck package at lunch next week.
MMM, a real tank with a real petc0ck... I think I hear my bike begging for some attention.

-WD