If you are wanting a "sissy-bar" type pack rack, then this company makes very very good ones.
They have been around forever. In fact I can STILL buy a new rack system for my '71 Suzuki T500, my '70 T125 Stinger, or the Vincent Rapide that's in my imaginary garage. All the usual travel-bike suspects are listed there. They make three different racks to fit the brackets, and I have usually got all three when I buy a kit as they are not expensive and the lower racks are good to have for just bopping around town or day rides. Their double, back-to-back packs work well too. The only problem with those is the temptation to put too much weight into them, high up.
Have a look.
Nigel in NZ
The mouth of a perfectly contented man is filled with .
-- 2200 BC Egyptian inscription