I sail a 1979 C27. Jotun's right - there's very, very little storage space. i don't know what layout your new boat has - but if you've got the dinette version, it's essentially like a very small travel trailer for 2.
Since you'll be living on it - I would highly recommend paying close attention to all the plumbing (head, fresh water, etc.). Ours is a disaster - with mold growing inside the water iines, etc. Since we just take her out for a couple days at most it's no big deal. For you, different story. Then there's the stove, blah, blah.
Finally, do a lot of research on heaters. You've got to be very careful. I'm sure there are lots of thread already here about this - and you'll get some good advice from other sailors here that have experience with them. But it's not something you want to screw up in such small quarters.
Finally, as to keeping her dry, most C27 owners I know agree that these old boats leak like sieves (ports, chain plates, vents, you name it). So unless everything's been re-bedded recently - just be prepared to work on a few leaks.
Definitely no reason you can't do it. But it's gonna be pretty spartan.
All that said, she'll sail great for you. They really are good old boats.