We have the identical underbody shape on Rigoler, a 1967 Morgan 34. We bought it from the original owners who said that a few were made like that to reduce wetted surface and increase speed. One of the drawbacks is the lack of any skeg to protect the rudder, and in our waters (Long Island Sound) lobster pots are a constant danger. I had a machine shop create a socket welded to "tuning fork" shape. I bolted it through the trailing edge of the keel and installed a discarded fiberglass VHF antenna into the socket with a light bolt. It seems to deflect lobster pot lines away from the prop, at least, if not the rudder. When it breaks (usually at the end of the season when the lift breaks it) I just go to the junk store and get another section of antenna. The stainless steel socket stays put.
We went aground a few years ago, and it bent the rudder. We had it removed and the stock straightened, while we were at it, we added about 2 inches of fiberglass to the leading edge of the rudder. It gave the rudder a little more balance. If I did it again, I'd go 3 inches.
We've made lots of other changes over the years we've owned the boat, too many to describe. We love this boat. She's fast and seaworthy. You won't regret any of the time and money you lavish on her.