I completed the lowering project this weekend. It resulted in about a 3" lowering of seat height, which is exactly what I wanted:
I used loctite on the connections at the linkage.
The first 3 inches of shock travel ("sag") happens when you sit on the bike (STOCK condition). That would put the rear tire closer to the rear fender with a shorter shock, SOoooooooo...
In addition to shortening the effective shock length by 1", I added more than 350lb to the PRELOAD to take up that 3" and now it BARELY SAGS when I sit on it.
I don't have the correct spanner tools to loosen the lock ring and turn the preload collar, and even if I did, that is a heavy spring, and you can gnarl up the collar badly (it is aluminum!). Those are aluminum threads as well, I don't like the idea of grinding them against a heavy duty coil spring anyway...
So, I used a coil spring compressor to make it easy to tighten the collar: