I know the WAIS caps at 155, but the Stanford-Binet test accomodates 160+, does it not?
Maybe, maybe not. Know why there's so much uncertainty? The population of possible subjects is too small. For a population with a mean IQ of 100 and a standard deviation of 15, the proportion above 160 IQ is only 0.003%. For a population of 300 million, that's about 9500 people. And remember that choosing the subjects would be a self-referential quandary -- you need an accurate IQ test even to select the population to submit to the IQ test.
So no, there's no basis for asserting accurate measurement in that part of the IQ distribution.
Extra credit -- Marilyn Vos Savant is supposed to have an IQ of 228. Oh, really? I'm not disputing that it's possible, only that there's no way to accurately measure an IQ like that. It's not reliable science or statistics.