Only runs 40 Degrees advanced

Is the cam cast iron or cast steel?

Metal has memory. If you bend the crankshaft on your push mower when you hit a big rock you can hit the crankshaft with a big hammer back into place.
Why does it have to shear the cam key? The key is tightened to the gear and cam with a bolt.
Only in Deliverance do you have to squeal like a pig.
Not saying the cam is Twisted just saying there is a possibility.
If the cam could be twisted, it may not stay perfectly straight, it would bind in the bearings, and squeal, as bearings tear up. A high pitched noise.
Key metal might be softer, bolted surface area may be limited. It is all theoretical.

I am stubborn, like to see cam stuff check ok, put that to rest. Then get to trouble shooting basic ignition problem.