I would not bother going back over it. Not that important.
It was almost convenient, now it is not!
Nah! I wanted to know, too.
Here are the numbers, now that the defective 12mm adapter is repaired:
Without KACR: 177psi
With KACR: 103psi
Timing advanced 1 tooth <Advanced the exhaust cam one tooth, i.e. the "MC Mod"
Without KACR: 175psi
With KACR: 123psi
Each test was repeated three times with no real variation in the numbers. The pressure gauge reached it's reading in four revolutions.
It appears that the MC mod increases starting compression by about 25%, which follows with what I experienced when I did the mod. There was some difficulty in starting from time to time, taking a bump or two to push it through the first compression stroke.
It doesn't seem to affect the true compression, just starting compression due to the change in KACR timing. It's relieving pressure earlier in the compression stroke when there is less pressure available to vent part of the incoming charge. Less stuff goes out the exhaust valve, leaving mores stuff to compress later in the stroke.
The KACR reduces the starting compression by about 40% and, from my experience, is pretty handy. Without it I'd get some nasty noises and kick-back from time to time (usually when hot) and the starter doesn't have enough grunt to spin it up quick. It usually took a bump or two, when cold, to get it going. That seems to follow what you saw with Keith's bike.
One of my plans was to install a Wossner domed piston to bump up the compression ratio. I wonder if I'd run onto the same "too high a starting pressure" issues.