there were other comstar variations however - like the boomerang comstars that came on euro bikes and the cx500 turbo.

The fronts are a direct replacement for any comstar wheel bike, but you have to source the rear from one of the Euro chain bikes (cb900f, cb1100F, vf750 for instance) if you want a match set since the cx500 turbo is a shaft drive bike.
They look like the old dymag or performance machine drag wheels from the 1980s.
There was also a tri-spoke comstar for smaller bikes like the MB-5:

doubt you will see one for anything bigger than 250ccs but still kinda different and neat.
BTW, the cb1100F came with a cast double three spoke rim:

I am not sure about what it takes to adapt these to a SOHC 750 but the 77-78F's share a lot of similar dimensions with the DOHC Fs from 1979-1983 and it would not surprise me if the front was a direct fit. The rear I have heard uses a different axle size but I can't confirm.