There has never been a Kona factory as such, so things like this couldn't have been done 'in-house' since they parted company with Paul Brodie in c1990. Except as HB says with ti bikes which were made first by Merlin, which was then an associated company, and then by Ti Sports which is in Washington state, fairly near to the Kona offices. The tell-tale will be the paint and decals - if they're original, I'll have to eat my words.
The tubeset is Tange Prestige Concept and this was used for the Kilaueas from 1993 to 1995, before that on Explosifs.