We have a very basic electrical system on our Pushpak (License built version of the Aeronca Chief). It consists of a removable battery mounted under the seat, a panel-mounted ammeter and leads to power the Intercom, Radio and GPS. The battery is removed to be recharged. Very simple and very cheap.
Airworld have a more sophisticated starter/alternator option, the MDL Starter and Alternator. You don't have to have the Starter if you don't want. Biggest problem with such a coversion will be the clearance available between the nose bowl and the engine to accept the alternator.
Airworld's web site is at
http://www.airworlduk.com/