I'm not sure about the swingarm, but I have an SSie shock on my '97 precisely because it's about 3/4" longer...supposedly helps handling, shortens the wheelbase, and puts a touch more weight up front, making it feel a little more planted. I detected no loss of stability. The mid-90's Supersports were pretty conservatively set up in terms of footpeg/bar position, wheelbase, and rear ride height.

That's why I would not be surprised if there were a difference in wheelbase between the models...someone here will know.