I don't think any existing measure could be Gaussian with any sort of accuracy at tail ends, because there you need too large sample size to norm the test & generally, the approximate Gaussian you get due to many random additive factors deviates by huge factors from Gaussian at the tail ends. Bulk of norming of a test comes from average people.

Ditto for correlations between IQ and anything. Bulk of reported correlation comes from near the mean.