You already have your answer. I'm afraid it certainly isn't a Ku, so if you paid a premium price for it, you may want to reopen negotiations with your seller.
I am fairly sure it is a 1999 Kula or Pahoehoe (which as far as I am aware are identical frames). 1999 was when Kona started using Easton Ultralite. The operative serial number is F811K 0814, which means it was built in the Fairly plant in November 1998.
Although it is a reasonable attempt at copying a Ku, I doubt whether the paintwork was done by a Kona-approved painter. The details differ from the way official Kus were painted - e.g, the decals are in slightly the wrong place, and the Kona Custom sticker wasn't used in 1998. However if you like it, then it is clearly an enhancement compared to the standard Kula/Pahoehoe paint.
It is a high-quality frame. The specifications quoted were - constructed of Easton Ultralite tubing with 7005 aluminum custom butted stays. Tubing dimensions: Top - 35 x 1.6/.8/1.3t, Down - 44.5 x 2.4/1.0/1.3t, Seat - 31.8 x 2.45/1.8t, Seatstays - 19 x 1.8t, Chain stays - 22 x 2.0t. Forged replaceable KRD dropouts. Made for 27.0mm seat post, 31.8mm front derailleur, 68/110 bottom bracket, and 1-1/8" headset. 3.5 lbs (18").
I don't believe that the tubeset used for 1998 Kus was any better than Ultralite. Nor do I believe that the tiny and little-known firm Enigma Design and Manufacturing, who built the Kus for Kona, did a better job than the Giant factory at Fairly. It isn't a Ku, but the point of the Ku was the custom paint job and you have a custom paint job, so you're not too badly off. The main thing is whether you enjoy riding it.
