Hello Huc,
Welcome aboard!
Find a surveyor with a resume and have the boat that interests you the most surveyed. Come along for the ride while he/she works and you'll get quite an education at the same time. Also check your local library for Inspecting the Aging Sailboat by Don Casey. It'll cost you some bucks up front but will level the playing field when it comes to making a rational decision. Make sure your survey includes the engine condition (oil sample) and rigging, or hire a mechanic and rigger separately.
If you need more help making a decision get the second boat surveyed too. I'd spent the extra bucks just to have that opinion on-hand. Anything your surveyor poo-poo's as a big negative will need to be fixed for insurance/marina consideration. Where I live they want to see a copy of a recent survey for both expenses. Anybody can hang out a shingle and claim to be a surveyor. As for a boat owners, not a repair yards, recommendation and ask for credentials if not to see examples of their work.
I've lived aboard my '86 35-3 for 2 1/2 years. For a single guy who occasionally single-hands and has company along for the ride, it is a terrific boat. Standing headroom, plenty of accommodation for stuff, and generally very roomy. I almost went as far as stating it is very gourmet. That's the claim to fame of a Mk III over a Mk II.
The advertisements posted don't offer enough information. The mast and standing rigging for the 35-III aren't in any of the photos. It has been out of the water so any blisters (controversial topic), if there are any that really matter, may have dried out and won't be discovered. There is more discovery to be done on what each boat is equipped with for accoutrements, such as electronics, winches, sail inventory and condition.
One last tiny tidbit of advise: Do not trust scum sucking bottom dwelling barnacle carbuncle tar balls eating brokers that both list boats and represent both the buyer and the seller. Just sayin'... there is conflict of interest in this "regulated" system of commission collecting. If you do decide to buy a boat your selection of expletives will expand but at a ratio far less than your feelings of utter joy and amazement. Of equal or more interest are the expletives used to express those very feelings of absolute bliss under sail. When I run out of those I'm often left very awed and speechless.
Regards to you and yours during your explorations...
T.