Seat post binder is on the wrong side for an early 90's Kona, the mags always made a big thing of it as it was more difficult for mud to get into the seat tube on a Kona. My vote goes for BSO with a straight fork.
OK probably going a bit too 'flights of fancy' here but looking at the top of the seat tube looks to me like some external butting going on there, also the drop-outs with cut outs don't say BSO to me, is it just possible someone might have converted an 88' with canti mounts, seen loads of disk conversions on later frames :?: