You can pretty much put any tire/rim on anything, just the amount of "fitting" will vary. IIRC the 2012 FXD uses the same 19" rim it's had for a long time. Dunno what's on the Sporty. You might have to use spacers to center it up and the axle diameters might be different. No big deal.
You might get lucky though and it will center, the rotor/caliper will be aligned and the axle's are the same. If the FXD and Sporty have the same forks, I don't see why anything would differ. The only other thing I can think of is the height of the new tire compared to the old and how it will look relative to the fender.
You can go on the Dunlop M'cycle site and look up OEM tires, and it will give you their height. I think if they're within a 1/2 it should look alright. If not, you might have to lower your fender a little.
It's not rocket science. Just measure everything, use common sense and go for it. It's not hard either. I'm no wrench and just an avg guy with tools, but I bumped up a size on my rear and it came out exactly as I'd measured re clearance.