I've owned my 1984 Cal 31 for 3 years. In that time we've mostly raced her, but gently (okay we have had two collisions and I did fly the spinnaker in 20 kn recently. I won't do that again.) Despite all that, the boat has stood up to it pretty well. At the moment I've got her torn apart to do a bunch of fixing, tweaking, and general maintenance. It's been a good exercise to see how the boat was constructed in the first place and what issues I need to monitor over time.
I would say that as a blue water cruiser, it could do it. I think the lack of good storage would limit you to no more than a 2 week passage, which could take you to just about any coastal or island-hopping destination. The other defects mentioned can be mitigated, like the large hatchway (I have a line that locks the boards in place).