Re: springer fork
I made a adaptor from a large washer. Drilled holes to match the hub and welded it to the disc, Don't try to weld the hub, First experiment warped the hub. The ideal thing would be a rim made for disc brake but this rim was large and had room for the bolts. It stops on a dime, but as I stated earlyer, I baby that front fork and always use the coaster and disc. Its there if I need it though, can lock up both brakes if I have to. Had just rear brakes, but could see my self over shootting an intersection.
Always do a pre-ride check. Make it a habit, and ride safe.