If you are going to dry sail the boat it won't need antifouling paint. I had a 21-foot boat for several years that I dry sailed in SF Bay and it had a run-of-the-mill topside paint on the bottom; no barrier coat, no anti-fouling. I never left it in the water for more than a day or two at a time, but the paint seemed to tolerate those short periods in the water just fine.
The swing keel in your pic looks like it needs a bit of attention, bit I've seen FAR worse. Sand and/or wire brush it, slap on some fairing compound, sand it some more, apply some primer, and some paint. In fact, just to be different, you could paint the bottom and the swing keel with contrasting colors (the more garish, the better