Hoping someone maybe able help me with information on what model tanks will fit straight to my 1982 R65LS?
It has been decades since I did this, I also suspect that the legality was questionable then and probably more so now.
With that caveat in place.......
You have two needs, the first is a tank whose base fits the R65 frame and provides clearance for the electrics on the RHS of the frame spine tube. The second need is a tank that has certain style cues that are appealing to you.
Take a fibreglass mold of the base of the R65 tank and a mold of the upper part of the tank of your choice. Adjust your two molds until they fit each other then lay up a new tank base and tank top in your molds (using petrol proof resin of course).
Release your tank top and base from their respective molds and join them - followed by enough layers of woven roving fiberglass so that the total thickness is at least 6 layers, finish with at least 3 layers of something like Dynel and polystryene, high wax resin (so you can achieve a decent sanded finish.
Your other alternative is the Indians on eBay who make aluminium tanks for BMW, have them graft the top of your choice onto a post 1981 R65 base.