I've ridden all the years '95 and up, often. The "97-'98 years have a different
cylinder than yours with a wider range of power. That great low-end with more high-rpm pull. Not a screaming all the way to the top like some bikes, but they keep pulling when the 95-96's signed off.
Then another cylinder concept in 2000, smoothing out the hit.
Haven't noticed much difference in the rest of the bike.
Something to consider- if your bike is otherwise in good shape, let Eric work his magic and your cylinder will be a known quantity, as opposed to guessing at a used newer bike. You will have better power that any of the stock KX's and better plating.