I sailed a 1986 O'Day 272 up from Cape Cod to Bristol RI years ago for a friend of mine. It sailed pretty well considering the not so favorable wind conditions that we had. It also moved along quite well with a Yamaha outboard on the stern. What really appealed to me the most about this boat was the fact that she could go into shallow water. I enjoy anchoring in shallow coves where no one can come in and anchor next to me at night.
The interior of these boats is superb. The stern sits a little higher than it should for my liking, but I favor sleeping in the forward V birth and this probably wouldn't be an issue if I owned the boat.
I would say the best way to improve windward ability on this boat is to buy new sails if the sails on this boat are old, soft, and appear baggy.
A friend of mine fixed up an old O'Day 22 stubby keel sloop and bought new sails for this boat and discovered a big difference in her sailing ability. Sails make the difference I think.