450 TAS would be a lot closer, but maybe still a little off. I know of some Hawkers haveing an VMO of 385kts. At 16000, that would not quite come out to 450, but could be pretty close. 16000 / 1000, x 5 = 80 + 385 = 465

probably off some without exact weather info, but maybe a slightly better idea. Just my 2cents.