My '29 has 6volt Bosch coils, like early VW Beetles. They are very good quality coils.
Mr.Spinale has an excellent point regarding wiring, that applies especially to the ignition system, but elsewhere on the car. When you have only 6 volts to work with, current draw for the same energy transfer id double what it would be in a 12volt system. Therefore, pay special attention to wire terminals and connections. Make sure contact surfaces are clean, use adequate size wire, the original Lincoln wiring uses at least 12 gauge for everything. The cloth covered replica wire is great, modern plastic coated wire works, if you are not trying for a high score on judged events. There is a lot of original wiring in my Lincoln Limo, but all wire has been inspected, replaced if necessary, and all terminals have been disassembled, contact surfaces cleaned with fine sandpaper, and re-assembled with clean nuts and washers. Headlamp connectors carry more amps than any other accessory wiring and must be well cleaned and tightly fastened.
Enjoy your Lincolns - they are made to be driven