I regret that the REFERENCE section of the website was not much help for you, but I believe you have overlooked some other resources that can be helpful.
Look at the REFERENCE article on the 16/17 hull. The KATAMA model is mentioned there as a variant of the MINOT:
Katama........1969 - 1976 Minot plus canvas windshield, forward seats
https://continuouswave.com/whaler/reference/16-17/The KATAMA model is also mentioned in the narrative description of all models.
A 1972 KATAMA is shown in CETACEA at Page 30.
https://continuouswave.com/whaler/cetac ... age30.htmlA modified MINOT is shown in CETACEA at Page 33.
https://continuouswave.com/whaler/cetac ... age33.htmlHowever, the boat seen above has a Reversible Pilot Seat (RPS), so it really does not fit as a KATAMA. There is a possibility it was specially ordered, or, more likely, an RPS was bought as an accessory and added to replace the original seating.
More important to your inquiry regarding the purchase of the boat under discussion, I doubt that there was a model year 2000 KATAMA made. Hulls with blue interior were not made after c.1972.
In general, a seller who offers a boat with a date or manufacture that is 30-years off from the actual date is either very uninformed about what he is selling or is being very misleading about what he is selling.
Regarding hull identification numbers, the federal hull identification number or HIN was not required until c.1972. Boston Whaler boats made prior (and after) 1972 all have a molded-in "stencil" number. The production year for some models and their stencil number ranges is partially documented. The 16-17 foot hull pre-1972 stencil number ranges are given in the REFERENCE article on the 16-17 foot hulls.
If the claim that the boat is a 2000 model were to be true, then the boat would need to have a federal HIN attached or molded into the hull. By c.2000 I would expect the federal HIN to be molded into the hull.