Ride height setting confusion

The factory height will set the lower control arm in the center of it's camber curve. When it is there, (which is nearly level from the rear, level being determined by an imaginary line drawn between the center of the T-bar and the center of the LBJ) you will have the least amount of wandering due to toe-change, as the suspension cycles up or down.
If you have modified any parts or intend to not use the factory alignment settings then your camber curves may no longer be valid.
To find your camber curve, you would have to ask the alignment tech to generate them, and it won't be cheap. Once you have those, they will show you what ride height would likely be best.
But the fact is, that if your wheels are not stock, or more specifically that the offset of the spider is not in the stock location and or the tire is a different diameter than what the car left the factory with, then it will wander anyhow.
So where do you draw the line?
Well let me tell you, lol; after a bunch of alignments (I was an alignment tech with unlimited use of the rack, after hours), The only way I could minimize the wandering was by creeping ever closer to the stock specs.
If you don't spend a lotta time at hiway speeds, this may not be an issue for you. But as for me, I live in a rural area and it's 20 to 30 minutes to the nearest towns and my car was my DD.
The Zerk is Not part of the measurement, you probably know that, and I suppose that what you are calling a rib, is actually the adjusting blade... which would be correct for the factory T-bars....... but may not be with the 1.03s. I know that with 1.03s, I could not use the blades..
I think I started with the LCAs parallel to the road using an imaginary line between the center of the LBJ, and the center of the T-bar, as noted above. This gave me a height of about 6 inches at the K-member, and plenty of room on the bumpstops.
I tried 5.5 but that put the suspension very nearly on the stops and altho it cornered swell there, the ride was too harsh for me. Eventually, I landed on 5.75 at the K. and it's been there for IDK, 18 years or so. Or maybe I went back to 6.0 I forget.
My 68Barracuda has a different spec than the Duster ; at 1.375