I have the C27-dinette like you're talking about. A couple of pics here:
Show me your sailboat's interior
I'm 6' (and ripped, of course). You'll have standing room only near the companion-way. And you'll only be able to stretch out in the pilot berth. And you'll continually bump the crap out of your head on the v-berth "door" frame top.
The dinette is actually a really nice option, because it gives you another good-sized bed - or a bit more layout room on the table while you're cooking. Storage, for clothes, etc. - is very minimal. You've got the hanging locker, but it's small. However, without an inboard, you've got a good deal of room in the engine compartment.
I replaced the holding tank in our boat - and re-plumbed the head. It's easy. The holding tank goes under the forward dinette seat and you just plumb up from there to the head, vent and pump-out. BUT, you'll be emptying your holding tank A LOT. So be ready for that hassle.
I personally wouldn't want to live on my boat (or a Cal 28). Especially in a cold damp climate. Too freakin' small. But that's just me.
I love sailing her and spending a few days at a time on her though!