What are you looking to do? Add an interior? Refinish the fiberglass? What's there now?
On my N17 the interior is all fiberglass. The underside of the deck looks to have been sprayed white and the other surfaces are finished fiberglass. All mine needs is a good buffing but I only use it as an equipment locker so that's not happening.
If you are going to actually use the cabin, based on mine, I would buff up the fiberglass surfaces, add cushions and enjoy.
I like the blue sails!