For the Gifted Individual Education Plan (GIEP) and 504, some of the information at these links and old posts may be helpful in providing ideas:

Hoagies' unofficial guide to GIEP - https://www.hoagiesgifted.org/unofficial_guide.htm

roundup on Individual Education Plans(IEP) and 504
- Wrightslaw: Writing Smart IEPs
- IEP recommendations
- possible ideas of what to include in a 504
- Knowing one's strengths and owning one's weaknesses (hat tip to Platypus101)