I AM going to change to a twin disk front setup one way or another.
Looking at an early Roadking I can't see a difference between a Roadking and Softail slider other than the obvious twin disk setup so my question is this.

What is the difference between the sliders that would prevent me from swapping them out, fitting an additional calliper and upgraded master cylinder without changing the tubes after all they are both 41mm.

 

FL Lowers, brembo caliper takeoffs with MC on ebay with FL front wheel with the 11.8" rotors and youre good to go.

Or get the conversion kit from Motorcycle Metal.

Or, get a 13" rotor and a caliper that works with 13" rotors. I found a source for 13" rotors ~$175 if interested.

Or, get the brembo caliper with adapter for 12.6" rotor and a 12.6" rotor from QTMI or Motorcycle Metal forum sponsor.

Or, get a bagger. Which also allows you a lot of great choices of rear suspension unlike softails.

Obviously something I have been looking into. lol

 

Man I wish I had dual discs in front of my Fatboy too.
Very expensive to do i would think .

 

The FL forks have a different mounting bracket for the fender. The fork leg is shorter and you will need longer cow bells. The FL fork on the touring bike is a little wider, will probably need to measure for new spacers. The front axle is a different diameter. Will need to also upgrade the front master cylinder to one off a touring bike.