TBH, if this student is already taking university calculus, the achievement tests will not tell you anything you don't already know about math, regardless of which one you use. None of them go beyond very basic differentiation and integration.
The only possible advantage to any of them for your purposes that I can think of is that it is possible (sometimes) to get standard scores above 160 on the WJIV. But I don't have those tables right in front of me, so I couldn't say for sure. And in any case, since the difference in meaning would be minimal up that far in the norms, you might get more real information from an out-of-level measure, such as a college placement test (e.g., Accuplacer, which, I'm guessing, they may already have taken). Or even from the GRE (although never having tried, I have no idea if one could register a child of this age for it).
What is it you are attempting to document with testing? That might give some additional direction to my answer. And are you more interested in understanding the ordinal performance in math or in the other areas? The "best" scores are not necessarily the highest, after all, depending on what the reason for testing is.