If you can get the WPPSI done in a reasonable time frame (i.e. there isn't something that you think that you'd get out of DYS that you need asap), I'd probably wait for those scores before applying. I say this because, if I am recalling DYS application guidelines correctly, none of the test scores you have are ones they consider. For the WJ achievement (which appears to be what you have there given the Reading/Writing/Achievement/Apps scores), they want Broad scores, not brief scores. I also don't think that the RIAS is among the tests they take.
All of this is probably due to the brief nature of these "brief" achievement scores and the RIAS, not because your kiddo is not a candidate for DYS. I think that they just want more complete measures, which these are not. I'd expect that they'd want a pretty good portfolio without broad or full scale scores for either achievement or IQ. I could, of course, be wrong though.
