I am looking for a recommendation for what size ceiling joists to put in for recessed lighting. I am restoring a historic home and need to put deeper joist on 2 of the sloped ceilings for insulation and recessed lighting. I was wondering if I should use 2x8 or 2x10 to be safe so there is enough depth for the IC housing.

good for you knowing you need at least IC lighting for your application.