Something In my #5 Cylinder?

I cast my vote in with the guy that recommended a complete teardown.
And agree with the guy who said something like; "you can pay me now or you can pay me later.
I haven't seen that kindof damage often, but every time I did, it was way worse than what the boroscope showed.
If I hadn't seen the no-other-damage, just a closed-gap plug...... it might be a different story. But that plug could be keeping a deadly secret.