Bambu- top shock mount stud is a 10x1.25 thread (if that is part of your question). If your original nuts are lost, you may have to order those, as many places do not inventory fine thread metrics.
Post a pic or two of what you're encountering. Maybe some similar issues solved with other brands. I think it was Hannibals build thread that also used YSS rear shocks, might have a peek at it. But I also think he fabbed up custom mounts- don't recall specifically.