If you get an older Harley single fire coil with the right primary ohms it should work. The duel fire coils have just two primary inputs. The single fire have three inputs. The singlefire coils are two coils in one housing. The three inputs are hot for one coil, hot for the other and a common ground.
In the J&P catalog they have a Dyna coil # 380-868 3 ohm primary. $149
A Datona coil #382-576 3 ohm $96.
A no name coil #383-676 2.4 ohm $93.99
You might find one on Ebay or someplace cheaper.