Hi Andy,
I might be teaching you to suck eggs, but,,,,,,,,
You can use the points in the mag, a moped 6 volt coil and a 6 volt battery - like the ones in a road lamp - and she'll run fine.
Add a modern condenser and you've got a running engine for less than a tenner on Ebay. The battery will last ages.
You could go to 12 volts with the coil, add an old battery and drive small alternator from the scrappies and you've got a 12v dc generator.
If you've a shed like some of us on here it'll cost you pennies.
Cheap, I am!
Cheers Stef.