My ds is like this, he is 14. Was assessed when he was 7, very very clever, but dyslexic.
He goes to the school I teach at . He gets support from SEN with spelling twice a week........but doesn't seem to go on any GT trips, although I have insisted he goes on the GT list. I think it is quite an unusual condition so very hard to know how to deal with. I also asked that his pen portrait included how intelligent he is.
One thing to be aware of: At start of Y7, pupils often sit CAT exams. I was furious with these, as he wasn't allowed extra time, although he was in his KS2 SATS. They gave completely incorrect and skewed results which showed his best subject to be Textile Technology............he is a level 7 in Maths, but not much good at textiles, and staff read and use the results of these tests
I have found that he is achieving above average in most subjects, BUT is hampered by his literacy problems, English is probably his least successful subject although he enjoys it, but anything with extended writing can be problematical.
You really need to push the school. The CATS I mentioned are meant to identify G&T, but didn't in my case. However you can insist he goes on the GT list as long as you have other evidence, eg aa assessment.
I would say, that his intelligence enables him to perform above average, but his ability is masked by his dyslexia and vice versa. I think 2% of population are like this. I do feel even though I work at his school, that he is a bit of an oddity, and no one really knows what to do with him....
PUSH,PUSH,PUSH, and raise conerns about early Y7 tests NOW!!!
HTH