Here's a couple of questions: How tall are you both and how much stuff do you have? The difference between the boats you are considering, in spatial terms and nothing else, is vast. Think living out of a sports car versus living out of a camper van.
Instinctively, I'd pick the 41-footer, but the Nauticat 33 is (as I am sure you will hear shortly) an excellent live-aboard choice and probably equals a 36-37 footer if it was a typical aft-cockpit sloop. On the other hand, 1973 is elderly for a salt-water boat...even freshwater, six-months a year early '70s boats here on the Great Lakes are showing their age, so that's a consideration. So is the state of the engine, sails, etc.
A bigger boat isn't just about the space, either, from the "living on a mooring" perspective: it's about the sizing and the robustness, for lack of a better term, of the onboard systems. A bigger boat may have hot, pressurized water and a place to shower: even six gallons of hot H20 will up the civility. A bigger boat will have adequate refrigeration, mechanical aids, maybe even A/C. And while all these devices can break and eat amps, it's possible to take a fraction of the money you didn't spend on a stupid slip and put in wind generators, a genset, bigger batteries, solar panels, etc. by which you'll be able to live on a mooring in conditions more amenable than eating beef jerky by paraffin lamp.
Not that there's anything wrong with that.
Just make sure the engine's good, because you guys will be sailing to the fuel dock regularly to take on all the gear that will make life more pleasant...unless your last name is Pardey.