You are also talking about an incline plane. If the nut is too low, the action at the 22nd will be unplayable. So if you intend to leave a stock nut, and not screw around endlessly with the height & taper...forget it. Precision at the nut will dictate precision at the 22nd & 24th. Let's assume that we use 0.030". For me that's right at the edge of playable on F's & Bb's.
I will also add that I love the enhanced string dynamics & tone added by the action change.
When I spoke with Matt Moriarty on this, he stated plainly that his impression of Jerry's guitars that he's held and measured was that they "were not extreme in any way". 1/8" at the 24th is not high action. This is what is shown on Waldo's Rosebud tab. And that his guitars were completely playable. I think every thing already pointed out is pretty cool. All hitting around a central point.
Let's assume for a moment that there is no nut. Dropping out the 0.030", and percieving the strings as an incline plane. The string angle (using SAS geometric theorem) would dictate that at 19.125" (Distance from nut to the 24th), the angle would only be 0.28 degrees. Pretty flat. That is also assuming that one drops a vertical bisection down from the saddles...and ignoring neck relief, of which the necessity for which is tempered by the advanced string height.
What would the height be at the 22nd (or at 18.344")? Using our calculated string angle we come up with 0.090. Now we add back our nut height for the block at the bottom and we're at 0.120".
We're talking pretty freaking flat. Sooooo....why all of this ....
In my opinion...the 7/64ths action is doable...almost. As Pete B. states, you can pull the saddle springs. Axematers Ebay sells a semi-Feitonized brass nut which also helps. Harry is great to work with.
But the real kicker, is that stretch of the string at the 5th and the 17th. The further you depress the string, the more the scale length is changed. It is very difficult to get anything other than a few cents sharp when depressing the strings at the 5th & 17th. You are effectively changing the scale length by that string height ...which is always true, but in this case it's a bit much. I've found the intonation to be great open & at the 12th. I definately prefer 3/32".
But then...guitars aren't really designed to be in perfect intonation at the 5th & 17th...that's just physics. Unless of course you just play at the 5th & 17th, and never play an open C chord.
One day I'll have to play with the geometry on an augmented neck angle, but logically it only seems to make sense (to me) with a harmonica type bridge....not a Strat style bridge.
Sorry for the long-windedness. The logic would have been more linear if I weren't missappropriating time from work.
p.s...Waldo...Completely agree. The Rosebud specs are more complete, and make the whole change infinitely easier to intonate.
"Hi Ho...the Carrion Crow...FoldeRoldeRiddle"