theoriticly you would not want to use carbon because of the different flex characteristics it has compared to the rest of the mast. there is a good chance it would work anyway tho.
kevlar has about the same flex characteristics of glass...if you use kevlar burry it deep under glass because it cant't be feathered down like glass or carbon. epoxy, s-glass, and wood should be good repair materials for the job. consider radiating the fibers of the cloth rather than lining them all up in the same direction. you may not be able to put enough material on the inside to take the loads that run inside the mast, but it's worth a try.

for me building a mast seems a little tricky because of the mast track. i'm thinking high density foam core shaped on a cnc machine and glass it w/carbon & s-glass. then gluing the track on with urethane glue. the track could maybe be a tube that has a groove cut into it.
sound realistic?