Hi citroen,
Sorry for taking so long to respond but I knew that I couldn’t explain what pictures could clearly show to answer your question; I needed time to get my act together and take good pictures (turned out a little fuzzy). As you can see, this IS a Model B starter (3 rather than 4 starter switch holes in the starter housing). And it has a new, modern Bendix for those that may be interested how this looks also.
Looking at the pictures, you need to find, in the flea market, an after-market, small housing to which the starter solenoid is mounted. It has a copper tab that maintains constant contact to the large copper terminal on the starter and is connected to one of the large terminals on the solenoid. This terminal also supports the solenoid atop the small housing. The other side of the solenoid with the large stak-on is connected directly to the positive terminal on your battery with a size 1 battery cable. The housing must be grounded in this case also. You must also obtain a replacement ignition switch with a momentary start position (much like modern ignition switches) that is connected to the secondary circuit of the solenoid that will close the circuit from your battery to the starter when you want to start your engine. Once the engine kicks over, you release the ignition switch, the solenoid opens, and the starter stops and disengages from the flywheel. This particular solenoid has a black button that you can push that allows you to manually energize the solenoid without having to turn the ignition switch to the start position – great for starting the engine while doing diagnostic work.
Similar to what many Model Aers do, I have connected a fuse block up to the rest of the Model A wiring but I use 20A circuit breakers rather than glass buss fuses as they are more forgiving.
Good luck!