It's been my experience that getting an IEP (or even a 504) for gifted students is pretty difficult - which is its own issue. In order to qualify for an IEP in my district you'd have to show that the disability is affecting your child's ability to access the general education curriculum.
The grade skip really wouldn't be the issue in my district. The issue would be that he's already reading well above grade level and his comprehension appears to be commensurate, which means he is not having an issue accessing the general ed curriculum. It is highly unlikely you'd get an IEP here for dyslexia.
If that's the case, you're definitely going to want a teacher who knows what they're doing and knows how to address some of these issues. I'd hesitate to pick the special ed teacher, however. Many special education teachers have no idea how to handle gifted students. The supports put in place for this student would and should look significantly different than a struggling reader with the same issues, but I'm not sure that would be apparent to a sped teacher who doesn't grasp how differently gifted kids think and process information.
The one thing I think you could push is the dysgraphia. If his ability to write is hindering his progress in the gen ed curriculum, you'd have a good case. You'd want to talk about how crucial writing is to understanding, especially as your son gets older. You want to give him the tools and the supports now, early so that by the time they will truly impede his ability in middle and high school he will already have a toolbox from which to pull. You should also be able to get OT for this as well. As part of that process, also consider asking for a Chromebook or similar. I've found that when kids feel like they can't write or if it's just too laborious, they won't. Give them a Chromebook or some other way of typing their stories and they're ready to go.
Good luck.
