"...If it is not listed it is open..."
N o, no, no! don't believe that part of Stainless' comment. A bunch of years ago we ran Nancy's little Ninja 250 on a record that wasn't in the book -- and therefore we assumed it was open. Two runs later we pulled it into Impound - - to be greeted by Tom Evans asking something like "Why are you here?" We told him about the no record in the book - and he promptly pulled out an "official" list of records and sure enough, there was an existing record in the class. Dang, we all decided -- it was a typo, so to speak, and didn't get entered in the Rulebook listings. So no record for us after all.
Lesson learned: Don't assume that there is no record just because there isn't one listed in the rulebook ('specially for "unusual" classes, like M-PS-BG 350).