If you think your Dd is at that Davidson's level, I would retest again, after a year or so, using the WISC. Did you have achievement tests done?
My dd is in a similar boat, she hit the 99.9% on WPPSI, but not the 150. Since she is bilingual, we plan to retest again with WISC in a year or two; and once (and if) she has hit an academic stride.
Her sister's achievement (w/o formal testing) increased dramatically in a year, so if we see something similar (reading advanced chapter books in K, for example), then we'll do the achievement testing.
As PP have said, there are portions of the WISC that are timed, bit not that many (blocks for example has a timed component). YSP will look at GAI as stated above, which removes processing speed.
Finally, I know of kids who have been accepted with a 99.9 WPPSI, good qualifying achievement scores, and a strong portfolio.
