Markie Mark (?)
Welcome to the madness. The S/N is located on the transoms. Unless there's been a major repair you should see it etched into the fiberglass and readable. Find that and I'll post the key that unlocks the number's significance.
Here is something I posted the other day to a poster about to buy a used boat. Couldn't hurt. Start here first.
"The biggest single thing is hull integrity. You need to look out for soft hulls, especially on the topsides directly in front of the front pylons. Put a palm down and press in looking for any deflection. Don't be afraid to lean in on it. Do the same everywhere else as you look for any signs of delamination. Inspect the holes the four pylons exit the topsides for any cracking or gaps.
Stand a few feet away from the boat fore and aft and spy all the way down the hulls both inboard and outboard. Look for any rippling, denting, or signs of repair. Repairs aren't necessarily a bad thing on an older boat if they're done well, just find them and know what you're getting. Carefully inspect the bottom edges for excessive wear from beach dragging. Press hard with fingers as you look for softness.
Standing and running rigging should be completely replaced anyway post-purchase as a safety precaution as you don't know how she was sailed, but its condition can be a sign of how she was sailed and what kind of shape she's in. Look carefully for hard wearing, frays, any splits and cracks. Even though it needs to be replaced ideally it will be in decent shape.
Inspect the tramp frame, mast and rudder assemblies carefully for splitting, cracks, repairs, etc. Check each rivet closely for a firm grip or any signs of being replaced. A good test is to lift each bow separately and see how the boat reacts. If it moves independently and comes up a lot b/f the other side then you have a weak frame. Do the same at each stern. A weak frame is reparable, just know what you're getting.
Another good test is to check for a square tramp frame by pulling a tape from front corner casting to rear corner casting. I found mine to be 3+" out of square once.
Treat it like inspecting a used car and look for obvious things. It's not a terribly complicated boat and once you slow down and take your time you will begin to see the right things.
Depending on its age and your initial budget you're probably buying an opportunity to bring something awesome back to life. If it has good bones you should be fine.
Another idea is to contact the local fleet. Who knows, with the right approach and a little friendly persuasion (free beer) you may find someone willing to look over a prospective boat with you. If anyone ever asked me I'd make a sincere effort to help.
Good luck, come back here often and ask questions and research specific issues. There is a TON of information here and awesome posters much more knowledgeable than myself who will get you going in the right direction. Without it I'd be dead in the water."
As noted be ready to replace all the standing and running rigging at a minimum. You may need to rake the rudders if you find you have too much weather helm. Weather help causes the helm to pull against you hard while underway. With mine it tired me out in less than an hour. I did this mod to the letter and it worked out perfect. Don't worry, TONS of material is here on that mod.