To make sure the stop circuit isn't grounded, remove the black/yellow wire from the power pack connector (pp side). If you still have no spark then the stator is to blame. If my memory serves me the stator on your engine has alternator coils, a charge coil and a sensor coil all contained in one potted ring.

Is the stator discolored? I think they were green when new. If it looks brown or has cracks in some areas or looks "burned" like it has been hot or arcing through the potting material it's probably toast. You might also remove the stator and check for chafing of the wires where they pass through the mag plate and externally in the harness leading to the power pack.

Since you already replaced the pack with a new one. Only a grounded stop circuit or the stator can be at fault.

You have two ignition coils, one per cylinder so if one of them fails you only lose one cylinder.