No, I thought that.I'm not sure the TX750 swingarm would fit an XS1. I think the early swingarms ('70-'73) are shorter, maybe narrower too, at least at the back where the wheel mounts. I think the pivot area is the same so it would fit there, I'm just not sure about clearance farther back. Maybe gggGary can help with this? He may have some loose early and late swingarms he could compare side by side.
Parts supplies are decreasing here-abouts.
yeah about everything on the early 70-73 frames is lighter flexier than the later 74 up parts.
Don't know what your 71 is right now but if it's anywhere near stock leave it alone, aside from clearances, maint, bearings, bushings, etc. Lot easier to start with a later bike (78-up) for better handling.
running a rather large rear tire
Always had a wobble at high speeds in the turns,