I believe the Harley will be one inch (1") handle bars and that some new-ish big-ish metric cruisers also use the "fat" 1 inch bars instead of the usual Japanese 7/8". Do some reading and see if this is true for more than the one example I could quickly find ("Honda Shadow ACE" - http://www.hondashadow.net/forum/53-general-discussion/93762-handlebar-size-1998-shadow-ace.html seems to confirm this). I think newer Harleys may have more complex switch wiring that the pre-1990 stuff that I have played with. Notably, there maybe special things like turning on hazards (push both left & right at the same time?) that won't work with the new single switch setup and require some thinking. Good luck!