"I would suggest getting a Brightsparks condenser fitted while you are at it."
I'd second that, provided it fits, they are excellent.
On my Panther magneto it fits inside the points housing, meaning that if it fails, you don't have to take the magneto apart, or even off to replace it. I can't see how one would fit inside my BSA Sloper magneto points, there is scarcely enough room for the points mechanism.
Cheers,
Bevan