If you are going to use electronic ignition, which I recommend, cut off everything you possibly can to save weight. If you are going to use the original magneto, you will need to leave enough metal to safely mount the coil. Be careful, as some have gone to a lot of trouble to trim it all down, and then had their coil mountings flex and/or crack later. Electronic ignition is the best both in terms of weight and engine handling, starting, etc.

Good luck,
AV8TOR