Most any of the standard models from 74 up will work fine, the later Special models work ok too. The big thing is the upper shock mount on the frame, on the Specials it is farther forward than the standards. This was done to give the shock a more layed down look to copy Harley.
Mag wheels can be used on any of these years. The only bit of hassle will be the brakes. Mags came with drum and disc brakes. If you have a drum brake bike it is easier to just swap drum brake mag in than convert to disc.
They rear disc brake mag wheels were used from late 78 to 80, in 81 they used a drum brake mag. In 82 they weht to spoked drum brake rears with 48 spokes and a 19 inch 48 spoke disc up front. All the earlier years used 18 inch spoked drum rears. the 70-71 used a drum 19 inch front, in 72 they started with disc up front, in 73 they redsigned the way the disc mounted on the wheel.
All the mag rear wheels are 16 inch, the trackers look better with an 18 or 19 inch rear wheel. If you do a bit of searching you will find info on how to use a Mag front wheel on the rear.
One more thing, there was never a CDI used on any stock XS650. It was a TCI.
Converting from the points of early models to an electronic ignition is easy. So don't let that stop you from buying.
Leo