The cap only goes on one way. Marking it won't help prevent getting it crooked, but making sure it is seated properly will. If you can get both clips on, then it's not crooked

Changing to electronic ignition won't help starting or power compared to a properly adjusted points ignition. So start by making sure it is properly adjusted (both initial timing, and using correct points gap). The gap wears during normal use, so it must be adjusted every so often and points replaced