I have raced on these boats and they are really good boats. With the board down they had very good windward performance for their day. With the board up, windward performance really was pretty poor but of course we almost never sailed upwind with the board up. The board does not contribute anything significant to the stability of the boat but the boat was hard to tack in higher winds without the board at least part way down. Occasionally, we would come around a mark after a spinacker leg and leave the board up by mistake as we started the beat. It was quite noticable when it was in the up position except during one very windy race where someone concluded that board was down and we were only sliding sidewards in the strong currents of the Wilmington River near Savannah. We only realized that the board was stuck in the up position when we went to tack and could not get through the wind without good crew work backing the sail.
I would not say that the boat is dangerous without the centerboard as long as you can count on your engine. (Which is not something that I generally would recommend, especially on a 30 or so year old boat) If the engine is reliable you should be able to motor off a leeshore, or motor through a tack if the winds piped up. You do need to get the board installed at some point if you are going to enjoy sailing the boat on the Chesapeake where we all seem to spend a fair chunk of time beating.