Try it out first.
Chances are really good that it will work just fine as is, and that all you will accomplish is to create a bunch of work for yourself.
I redid a canoe that was originally strip and canvas, that had been badly recovered in glass. Took me a couple days with several different electric sanders to knock down the glopped on resin, in some areas it was 1/4 inch thick.
Essentially, you will want to assess the state of it, and see if you really think it worth putting the hours in.
If the glass that was used was mat (random direction fibers) you are pretty much going to have to decide where to stop sanding. If it is cloth (weave fibers) then you will be trying to decide whether to cut through it, whether it sits on the structure (good) or was placed on top of large lumps of resin (not so good) and go from there.
Skip CTire, and find a glass shop! Check the boat places too, if there are any around. They deal usually in larger qty units than CTire does, and they may even sell cloth and mat by the yard. Resin and hardener, as well as cloth or mat, should be MUCH cheaper there. But check prices. I've been wrong before, eh.
There are a couple decent books out there on Glass work. You will be money head finding the books first, and reading up on what you will need.
Watch the catalyst for the resin! Metyl Etyl Ketone Peroxide (MEKP). Get it in your eye and you see only out of the other one for the rest of your life.
Cheers
Trev