A good place to start would be the library / book store. Consider
'Fiberglass Boats' by Hugo Du Plessis or 'Upgrading the Cruising
Sailboat' by Dan Spurr.

If you're truly going to 'gut' the interior, and you don't want to
spend a lot of time, stop. No point in proceeding. If you've got 6
months of 8 hour days, it's likely a matter of removing all of the
interior fittings, plumbing, joinery (cabinetry), tanks, electrical
wiring and devices, etc. It's unlikely you'll be able to reposition
the engine, but this would be a good time to consider re-powering
(especially if the engine is from '72) which may also mean
reconfiguring the engine bed (motor mounts),

With all of this removed, you'll likely be down to full (structural)
and partial bulkheads - probably plywood - which have been 'tabbed'
onto the hull with a layer or two of fiberglass strips. If done
properly, the bulkheads actually rest on a foam /balsa beveled spacer
(see Du Plessis) that prevents the bulkhead from forming a 'hard spot'
where it contacts the hull.

Now comes the fun part. With a large grinder equipped with a sanding
pad and 24 grit paper and you wearing eye, ear and lung protection,
grind away at the junction of the bulkhead and hull-side (carefully)
to cut away the tabbing, thus freeing the bulkhead for removal.

If it's a structural bulkhead (one that is attached to all points of
the hull and cabin / house) consider adding temporary bracing fore and
aft of this bulkhead prior to its removal.

If the hull is cored above the W/L, it's likely balsa (...'72) which
should be inspected for water ingress / rot.

Good Luck.

Mike Worrall
Los angeles