Hi

I have on hand a rebuilt double stack early coil plate with corresponding 5/8 magnets for a 1912 engine I am working on.

I am planning to install the early setup above on a ring geared flywheel. Am I going to run into any trouble down the line when it comes to installing it to the engine?

The reason for not using the original flywheel is because the mating surfaces are badly rusted and I don't know if it could be machined back okay.

Let me know your opinions or experiences.

While there is no problem with installing a ring gear flywheel in the earlier pan, those ring gear flywheels are built for 3/4" magnets, so yes, there might be a problem with using it directly, i.e. with no modifications.

If it were my car, I'd locate another early type flywheel. There are a lot of them around, especially since so many guys have installed the ring gear flywheels against the day they may want to put a starter on the car.

The one i have has rust pitting on the mating surface - is it easy for a machinist to true it up?

It could be done, but it's cheaper and simpler just to replace it.