Note that I'm pretending that the score is from 2012, the SAT is normally distributed with mean and variances reported here, the test-retest variability has a std of 30, and I'm multiplying Gaussian distributions as discussed here. The 2nd and 3rd assumption is good near the middle but weak at the ends; the calculation done at 800 is almost certainly incorrect, because we can't tell the difference between a 3 or 4 sigma mathematician, both of whom would most likely score 800; we could correct for that by integrating, but that's too much work for a brief explanation. Note also that the truncation of the normal distribution by having a max and min score probably underestimates the underlying standard deviations, and so the effect would probably be more pronounced with a better test.

I'm not sure you're using the right numbers for the variability. The material I'm finding online indicates that '30 points with 67% confidence' is not the meaningful number, but simply the r correlation between 2 administrations of the SAT: the percent of regression is 100*(1-r).

The 2011 SAT test-retest reliabilities are all around 0.9 (the math section is 0.91-0.93), so that's 10%.

Using your female math mean of 499, a female score of 800 would be regressed to 800 - ((800 - 499) * 0.1) = 769.9. Using your male math mean of 532, then a male score of 800 would regress down to 800 - ((800 - 532) * 0.1) = 773.2.