Joe already mentioned the standing rigging, O'DAY originally used 3/32" wire, it should have been 1/8". D&R sells the upgraded rigging as a package, but any local rigger can make new for you.
From the pics the boat and motor look good, but I won't give a definite judgement just from pics (Craigslist pics are usually just fuzzy enough to hide things).
Condition of the maststep area, mine rotted out under the deck (boat must have been a Friday or Monday boat..... maststep did not line up with the support pipe below the cuddy deck, so cuddy deck (floor) had cracked, previous owner fixed, but.... it was a pretty big BANG when his repair let go while I was sailing! Joe mentioned the Centerboard, but I'd want to check the lines/cables that raise and lower the CB. I'd say that this boat is a 1974-6 range...... the mainsheet is mid-boom which was used on late 1974 models and later, mast appears to be gold-annodized, that was a mid-1970'd feature.
For comparison, I paid $1400 for my 1979 DS II in 1996 with a trailer. I needed to replace the self-bailer, the bilge drainplug, and one spreader (spent about $45 from D&R at the time). Trailer needed new axle, springs, hubs, bearings, wheels, and tires 2 years later (around $400) but I'm in Saltwater and previous owner did zilch about maintaining trailer.
The outboard price is not bad, if this is a freshwater outboard. 6hp is a little big for a DS II, I use a 4hp and could almost get away with 2hp.
PS: Joe, I like the dodger on the Sturdee Cat! I recognize that ramp too..... my Dad and I used it a few times while exploring the Taunton River with our 14' powerboat. Kind of a steep road to enter/exit though! Not to mention the road going by is one-way now.