If you haven't figured it out by now, you MUST discount everything Larry Shepard writes. I don't know how he gets paid for what he does. For example, the "75 and up blocks are thinwall castings, can't go more than 0.030 over" LIE, disproved by our own AndyF.
I also blame him for the lie that you find the purple shaft duration at 50 lift by multiplying advertised duration by 0.85. Isn't so! He also writes very condescendingly about why MP doesn't or didn't release REAL 0.050 lift duration numbers, that it would cause too much confusion for users, as if we're all the village idiot.

So you see, I'm prejudiced.

R.