Raise the bar so the lower bolt holes line up with the upper openings. Loosely bolt them in place to hold it. Replace the bolts that go into the very bottom level with an M8 threaded bolt that is either 100mm long threaded section or 100mm longer than stock. Not sure on that part, but I do know that raising it works, the replacement bolt should be about 3/4" longer than the original. Ran mine like that for a while until the late great Max Morley (R.I.P. my friend) bought the rails and bar from me.
Mine has a close to 3' tall sissybar off an old air-cooled metric 4 cylinder bike. I know there are pics on the forum but let me swap computers and I'll put one up here... hang tight...
Here we go, just drill your fender/rails to match the donor bike's spacing...
and
Piece of cake. You can put ANYTHING on a Savage...