Do you have to add oil to the crankcases between oil changes?
Just remember witnesses are notoriously unreliable. But for arguements sake, the smoke could be because you are a tad rich, worn valve guides/seals, worn rings (probably not), or a combination.
Also remember that the flatslides will dump hug amonts of fuel into the combustion chambers if your throttle style is of the whack-it-wide-open religion. Smooth roll-ons allow the engine to respond without dealing with momentary over-rich conditions before the RPMs rise.
Whatever the cause, it should be relatively minor to correct. Do not succumb to the idiocy that has gripped many people and figure that it isn't worth putting a lot of money into "an old bike like this" The correct philosophy for calculating the correct amont of money to dedicate to a 91-97 Supersport is as follows: How much? Do you accept checks? Repeat as necessary.