One of the best of the folkboat derivatives and one that can usually be bought cheaply, was built by Whitby in Canada in the 1960's and was marketed under several different names including Walton 25 and Whitby 25. At least some of these had lead ballast and amoungst Folkboat aficionados were considered to be closer to the higher stability of the wooden folkboats than most of the later fiberglass derrivatives.
I owned a 1949 lapstrake, wooden Folkboat back in the early 1970's and these were spectacularly wonderful little boats. Although very cramped and limited in carrying capacity, they were a true delight to sail in almost all conditions. I would never call them moderate beam. They are clearly on the skinny side and so had tendancy to sail on their ear.
I have also sailed a Folkboat with a junk
rig that attempted to replicate Blondie Haslers' "Jester". My sense is that chaning to a junk
rig took a boat that sailed incredibly well in a wide range of conditions and turned it into a boat with mediocre sailing capabilites except on a reach, and even there it was not noticably better than the stock
rig. Maintenance (due to chafe) on the junk
rig was killing this guy as well.
I really think you would be better served to keep and update the stock Folkboat
rig. This was a strong, simple, and very easily handled
rig that was easy to adapt to changing conditions, especially of the
rig is updated with a full batten main, and a couple reefs using modern 2-line slab reefing. Based on actually sailing these boats I would suggest that Folkboat
rigs do not need reinventing, just a small amount of tweaking.
Jeff