You'll need to weld a Foot peg bracket to each lower frame rail, and then determine if Dyna or FXR based mid cotrol brackets will give you the clearance and positioning needed.
The outer primary cover will need a center panel with the proper hole and seal in it to pass the splined shifter shaft through, you might be able to get a Dyna one to fit or you'll need to machine a stock FLHT one..
The inner primary wil need to be machined for a hole with a proper seal put in as well to pass the splined shaft through, since there is no stock inner FLHT primary that has it.
From there you'll need to fabricate the shifter linkage from the shifter shaft to the shiter arm on the tranny. That will be easy, since there are lots of aftermarket pieces readily available for that.
On the Brake side, there are mid control Brake Brackets made for softails that bolt to the outer tranny cover and the engine point cover. You'll need to machine an existing one to fit, or build one similar to it. This will allow you then to mount a rear brake resiviour and pivot point for the rear brake pedal. Also, you should be able to leverage the stock rear brake switch to work with the custom setup or get and aftermarket switch to wire it in.
Sounds like a lot of work, but it is doable. Or you could go the other way and build the SuperGlide into a version of a FLHT. That will cost a hell of a lot more, but would alow you to keep the bike you have now and leverage the ergonimics you have going for you now that work for your back.