need help!!

I recently bought what looks like a series 5 rer the previous owner had it running until he charged the battery with jumper cables to his running buick.

This resulted in him frying the coil.

Here is my problem....

The engine is a Wisconsin Robin WI-450V

Evidently coils for these are rare to non existant.

Does anyone know of a source for one or a conversion/usable alternative coil?

I would hate to break up an all original mower just because of a dead coil.

I Will post pics of it as well as the full ID numbers as soon as I am home during daylight hours.