Blowby 58special

[simonbuick]

hello buick lovers.
my buick special 1958 is bothered by blowby.
I'm going to do a compression test, but does any of you have experience with this?
I checked the cylinders with an endoscope this afternoon, and they are blackened.
Can this be cleaned without doing further damage to the engine.
I would like to hear from you .
greetings Simon