I, too, recently bought a 1978 Cal 2-25! I've had her since July of this year. Your boat sounds very similar to mine with the winch on the port side. But, I have a boom vang. However, I'm not sure if it was originally with the boat or the previous owner put it on. I'm the third owner of the boat.
I've recently had a problem with the spreader on my starboard side. I was hearing a pretty significant clanging sound when I was on a port tack the last time out. When got back to the marina, I found that my starboard spreader was very loose. I went up the mast today and determined that the loose spreader was angled down at about a -5 degree angle from the mast while the other spreader that is ok was angled up at about 5 degrees off the mast. Can you confirm for me that both spreaders should be angled off the mast or should they be perpendicular to the mast?