"How do I open an exhaust valve? Turn the engine by hand using the crankshaft nut until it is just before TDC on the exhaust stroke."--PEH

That is what I was afraid of..... that might require two or three strokes of the piston before you got to that place...with the junk traveling with the piston and ring.... It would be best to start taking out any particles beginning the first time the piston starts downward ( turning the engine in the proper direction all the time ).

" It was SOP to blow chips and debris off machines. I never knew of a machine that had to be repaired because of blowing off the chips."-PEH

I did not say repaired... I said cleaned.... most machines like that will take years to wear out even abused... we also don't know what tolerances the machines which are subject to that sort of thing were being used for by the end of your ten years... lots of sloppy machines continue to be used because the operator allows for the problem and fixes it with another procedure... if you can't hold a close tolerance on a lathe over a long distance then you get as close as you can and then grind to specs...
The best example of the former was the Triumph Motorcycle Co... when the guy that had done the boring for decades retired they could not find anyone who could compensate for the old machine's quirks... and they had to close the company..

It is now standard industry practice when cleaning tooling machines to use oil to flush...as compared to compressed air...