You'll probably have more luck researching the Ensenada 20 -- a very similar boat (the RK20 is another version). Lyle Hess design -- VERY solid little boat. The Balboas generally (but not always) have an external swing keel -- it doesn't retract into the hull. This means the boat doesn't pull onto a beach and is tougher to launch, but it removes the Great Wall of Ensenada (keel trunk) from the interior, making it less cluttered. The E20 has about the largest cabin in it class, due to its flush decks and small cockpit; the B20 is pokier down below. The E20 has a ridiculously over-sized mast and no spreaders; the B20 spars are a bit more proportional and generally use spreaders. Either set-up is fine.
These are not fast boats. They weigh in at a 1700 lbs and carry only 174 sqft of working sail, and their PHRF rating is around 300. If you live in a light air region, a big genoa is a lifesaver. You'll have trouble getting more than two in the cockpit, though one passenger could lounge on the deck. They typically sell from $700 to $2500. It's a good little boat and a great choice to learn on: stable and forgiving.
Some B20/E20 links: