Welcome to sailnet. You really generally shouldn't revive threads that have been dead for a while. Often, you're better off starting a new thread, and posting a link to the old one, but you can't post links until you have ten posts...
Don't use pine furring strips... unless you plan on encapsulating them completely in epoxy, since they'll keep changing size as the humidity level changes—they also are not very resistant to rot and swell when they get wet...which they will.
Don't screw the furring strips in to the hull, epoxy them—especially if you have a cored hull. Screwing stuff in to fiberglass is a losing bet, since it is far too brittle to really tolerate it at all. Screwing stuff in to a cored hull is plain stupid, unless you like the hull to delaminate.
Put insulation between the furring strips and then put the ceilings on over the insulation. (BTW, FYI, the interior vertical surface inside the hull of a boat is referred to as ceilings, the "ceiling" is actually referred to as overhead.)
Use cedar, white oak or some other rot resistant wood. Some people have had good success using balsa for the furring strips and glassing over the balsa to give it a bit more strength. The furring strips don't have to be very thick btw... 1/2" is usually sufficient. BTW, make sure the screws you use don't go through the furring strips into the fiberglass.
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