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FWIW, I just kept using my old Bosch coil when I switched from an imitation 009 to a MagnaSpark II. All has been fine ever since.
The folks at CBP told me you bet, fer sure, you can use a Bosch coil. They just don't make as much profit out of the transaction in that case.
My take has always been that a Volkswagen engine shouldn't need a space-age ignition system to, like, run OK because, well, Volkswagen. And I'm also wondering just how space-age a CB ignition coil could be inside, anyway. I mean, would the electrons really notice a difference?
Coils in general are happier the farther they are from heat and vibration. Mine is mounted in the left, rear corner of the engine bay and not on the shroud. It doesn't look as nifty mounted there as it would on the shroud, but I figure I'm not a stylish guy otherwise, and having my coil on the shroud probably wouldn't help me get invited to the right parties, anyway.
Just saying.