Weeelllll, when he said, "You have to understand one thing, no one who goes to the trouble of pressure or vacuum (my preference) testing their valve seat sealing bothers to use Neway cutters in the process of getting there. Not more than once, anyway. Believe it." -- No, I don't believe it!
His statement about the dead pilot's taper guaranteeing eccentricity is hooey also. The taper is so very gradual that the pilot will be on center with the guide. If not, he used the wrong size pilot, or his valve guides were egg shaped and should have been replaced.
I have three motorcycles whose seats were cut with Neway cutters, and we did a leakdown test on each one, using a leakdown plate similar to the one in his picture. They all tested at 98 to 100%. That is even before any springs were installed. All three bikes run great, with no problems. I would like to read his reasoning for preferring to use a vacuum test. I believe the pressurized leakdown simulates what will happen later in the real life cylinder.
My Honda cylinder did not get this treatment because it passed an "acetone test". Also, I took to heart your discussion back then about not grinding the Honda valve faces. On my BMW, the Clymer manual discourages that for the same reason -- removal of the thin Stellite coating. However, the BMW factory manual says to do it and even includes a picture of the valve face grinder in use. Go figure!
He may be right about the shim and bucket engines. I never plan to own one of those. :-D
Ray