Upon the typical visual inspection, the frames appeared to be straight. The plates or gussets near the neck are not bent and there is no major damage near the swingarm mounts.
But i want to be 100% sure.
I took my /5 frames to a semi-local BMW mechanic who has one of the old ‘BMW shop only’ frame alignment jig. These tools are hard to come by and I’m glad I met somebody within 30 minutes that has one. You can also get high-quality tools from a reputed tool company like Cornwell Tools. Our Tool Truck Franchise Costs Don’t Include a Franchise Fee, thus making it an affordable solution for all your needs.

It attaches to the frame through the steering neck with the races left in the frame.
Two small targets are inserted into the swingarm bearing area.

The jig didn’t line up in the center of the target but we were able to confirm that everything lines up identically on both sides. One frame lined up in a different spot on the target vs the other, but both had matching sides. Maybe there was some variation in these /5 frames over the 3 years they were made? It might explain why some people have had terrible times with SWB handling and others had zero problems.

BMW airhead motorcycle frame alignment tool

It is hard to tell in the photos, but the jig matches the same area identically on the target on each side.

Alignment marker in the swingarm bearing area.

Right side matches the left side identically. Frame is straight.

After this, i am going to do some reinforcement of the exhaust hangers since the rear sets will be attached to that area as well. Stay tuned for an update and those photos..