Remove stator cover and see if flywheel key sheered or maybe they did not even put key way in . You will need a flywheel puller . Same one fits bunch of old Honda 2 stroke bikes.
I have no input on what happened to ignition . I’ve never had any issues with any of my bikes ignition systems. But I bet your issue is previous owner related just like this above issue was .
Maybe cable is routed wrong . Years ago I had an issue like this on my xc200 . But twice when it did it was in tight woods and crashed both times violently . I made a thin piece of steel and drilled holes in it . One end went under screw adjuster on top of carb and cable was routed thru it...
Don’t forget to address your reeds not fully closing . I hate that boyseen setup they used back then . They could have made a better hold down bar . They should have made it with slide wedge or angle to it . They just flat and don’t hold the petals down good and flat
You ordered the part that bolts in with two screws and had linkage rod ? Not the part with bubba welded stud on it ? I thought you ordered the welded repaired part ?
It might but you would have to rev the engine and open power valve at same time and not positive if you can time it all correct . But could try or just wait for lever . Don’t forget new lock nut with the teflon and washer . Make sure linkage rod is not in bind when you tighten it all