I will add, (now that Fred has put the cat among the pigeons),..............XS650 Specials with mag wheels..............
All Specials have 19" front and 16" rear.
78SE, 79SF, 80SG; Have disk brakes on the front and rear so a swap into a Standard or Special Spoke wheel model would necessitate frame and swing arm modifications and Brake actuator change. Not a straight swap.
81SH; Has Mag wheels with the 16" rear mag having a drum brake. This year/model is a one off in the US, having a set of Mag wheels that are a direct swap into a Spoke wheel models without any frame, swing-arm or brake actuator modification.
Again, have a look at the model ID thread i linked to to compare the information given against the relevant models.