have you looked at Mike's XS?
https://www.mikesxs.net/
A US based supplier they do have neat upgrade parts for the XS disc front end, esp to convert to dual disc.
FWIW, upgrading to a later xs650 front end and converting to dual disc is probably the way to go for you. All the other methods you are talking about are not a bolt on, they all will require some sort of fabrication. If you search around here you will see guys who have used the later xs650 35mm forks on cb750s just to get better caliper setup.
The GL1000 forks are long, they will need to be shortened if you plan to use them. Not by much but it is extra work.
Yes I know mikesxs have bought several things from them, although their shipping is hell expensive.
The '72 year XS650 (and all the early 34mm fork XS650s) actually have a shorter steering neck than the rest of the models that came later, I know of no steering stem that will swap around easily, in all cases I will need to swap out the steering spindle, so whether I go 37mm or 35mm same thing really with regards to steering stem.
Thanks for the heads up on the GL1000 length will take that into consideration. The XS650 35mm front end would be more work than a CB750/4 fork as they don't have the lower fender mounts which I'd have to weld and then machine to get right.
Really just want to know if the GL1000 forks are a significant improvement if not then maybe 35mm CB750/4 forks will be just fine.
