I have the 1986 model of that bike, and it has the same fuel tank setup. I have always wondered what I would do if that hose got damaged.
I was thinking that it may be possible to stop by a diesel mechanic and get a piece of fuel hose from them. They should have stuff that big. With some heat and patience you may be able to get it bent into the shape you need.
Another thought I had was to use radiator hose, but I don't think it's gasoline safe, so I don't think I would try that.
Another possibility would be to bend some 1" (but don't quote me on the size, measure it!) copper pipe using a conduit bender into the shape you need and use the remains of the original hose to cut some 2" pieces that can be used to attach it using hose camps. (a piece of rubber hose and 2 clamps at each side of the new metal pipe.)
All of these are just ideas and I haven't tried any of them.
--Justin