Honestly at the age and condition you're talking about, most of these boats come down to just personal preference. They're all similarly built hand
layup FRP of about the same thickness. Most of them were made in Costa Mesa by the same group of people day jobbing at different factories.
You should be considering that you're
buying a
hull, a
mast, and a
keel. If all three are true, everything else is easily fixed.
A 6hp outboard that will move any of these boats at
hull speed is $1500. A brand new suit of sails is $1500. New
rigging is <$1000 professionally done.
As long as the winches are properly backed, the
hull floats, the seacocks are nonexistent, and the transom mount is solid, you're in business.
The only things that are truly difficult/nonstarters on boats of this type are leaky deck/hull joints under the rub rail,
mast step breakage, loose/leaking chainplates, and
fiberglass damage. If there's an unusual system such as a daggerboard/centerboard or a
water ballast tank, that will need a quick look as well.
But honestly, if it floats, and if you can wash it down with a hose and it stays dry inside, and the mast is straight, and it looks like all the pieces
parts are there, you're in business at this
price point.
Trailers are a different story--No trailer lasts 20 years, and whatever trailer you get with these boats will be on its last legs. I would inspect them thoroughly. New axles and tires will run about $1000. New draw bar will run <$1000. If you like the boat but the trailer sucks a new trailer can be had for $3000 and a serviceable used trailer can be had for $1000.
If you're not the guy who likes scrubbing down the
interior, painting the exterior, and rebedding
hardware, and repacking
wheel bearings, I suggest spending an additional $5,000 now to get something vastly younger and more "ready to wear".