I have a list of all the bulbs both 6V and 12V for the Model A and an electrical parts chart. If you are interested please send me an email
[email protected] and will send them to you. If you do go to 12V, consider putting on a modern barrel drive starter bendix, less chance of breaking off a bolt on the old spring type bendix. Converted mine back to 6V from 12V since getting the electric wiper motor rebuilt, and finding the correct Power House Generator.