Try a search (blue "button" at the top) on rotating mast on this forum. In the past, there have been at least a few discussions usually involving 26D’s of people either putting on the rotating hardware from Macgregor and in one case a Hobie 18. I think Mac used to sell the rotating base and spreader for under $300 which seemed like a good deal.
I thought about it for my 26S but decided it probably wasn’t worth doing. The 26D would make more sense and it would make the boat incrementally faster - but your still probably going to get beat by someone with a better keel (like a J24). And if you have the boat outfitted for comfort (i.e., adding weight), still slight improvement - but still slower than lots of stuff and it makes even less sense. I think if you put on a rotating mast, the boat would need to be bare bones light weight to take advantage. The thing these boats do better than most is trailer - setup, launching and towing. Anything that is faster is a huge amount more difficult to get in and out of the water. Ill just enjoy having something that is very easy to trailer and still somewhat fast.
Part of the reason I put the rotating mast on the small boat is that I sail it at higher elevation where the wind is gusty and changes fast. One benefit of the rotating mast is that it works well on just the main especially in windier conditions. I have a wire luft furling jib on this boat and just by either having the jib up or not, I get a really huge wind range from the boat. On the big boat, you can get the same range by just reefing the main which works nicely and the jib negates some of the benefits of the rotating mast. On my small tippy boat, reefing the main in the conditions where I would need to do it are pretty much out of the question.. but reefing the jib - very easy.