ironhead cam postion

i have a 1983 Harley Davidson Sportster.this is my first motorcycle i have been redoing for about 6 months. i was having some issues, the bike was breaking up at high rpm. ( though my powerband). so i decided it must be an ignition problem. i decided to rewire my bike. i bought a new voltage regulator, coil, rewired everything, and had the generator rebuilt. the last thing i need to finish my bike aside from a batter is the "cam shaft position senor" (im not sure if thats the proper terminology so correct me if im wrong). i would like some feed back from everyone on where i can find one for a decent price and of good quality. and any tricks or tips i need to know about ironheads