I made that "leaf spring" out of flat and tube stock- it is strictly ornamental. I like the leaf look and it functions as a fender.
I am using functional springer fork like this one:
Forks - 20" Springer Fork | BikeWorldUSA | Bicycle Parts and Bike Accessories
It works fine, but I have the spring bolt tightened down to angle the fork forward a bit. This limits travel some, but it seems to work fine. I am sure that more modern designs ride better, but if I wanted a more modern design....