The first question I would ponder is what IQ test did they give him... In some schools they sometimes give very flaky tests that are cheap to administer yet are also prone to have score that are shall we say less than accurate.
I'm not saying that your son isn't really 142... but with the margin of error in some test he could easily be 15 to 20 points higher or lower...
I think you might first consider finding someone outside the school that could test him and look for any problems. Dyslexia could be the reason he doesn't read and is disturbed by people trying to push him to. If he has some problem like that he needs to get that address before you worry about the education, as that problem ignored is going to make it all but impossible for him to achieve much in school, gift or not.
