There is nothing special about a headset for a springer vs one for a rigid fork. All that matters is that the headset is for the proper dia. steerer tube ( 1", 1&1/8", etc.) and that the Stack Height fits in the amount of steerer tube you have available. For bikes that have one piece cranks the headsets that are available all have pretty much the same stack height, so this isn't really much of an issue. The serations you speak of are just a way of locking in the adjustment. Not all headsets have these serations.As for the cups you asked about Head sets come with two cups the bottom cup presses into the head tube and the top cup threads onto the steerer tube, or slides on in the case of a threadless steerer.
ocscully