KYB shock?'s

I sort of disagree, changing the ride height will change the wheel rate (agree that it doesn't change the spring rate - that's fixed by the dimensions of the bar).
It falls into nearly the splitting hairs zone, but changing the pre-load setting changes the angle of the LCA. Since a Moment (torque on the t-bar) is always, always, always a force (weight on the lower ball-joint) X the perpendicular distance to the axis of rotation (inner LCA pivot) then changing the angle of the LCA will lengthen or shorten the effective lever length. The angle change isn't great, so the lever length change won't be large either, but some drivers should be able to tell the difference. Not all, but some.

As to the OP's question, all stock / t-bars & rear springs on my '65 Valiant 2 dr. I put KYB's on it to get it drivable. Figured to put something better on it later. I noticed what I've always noticed about KYB's on any car that I've ridden in or driven with them. The ride tends toward the harsh end of the spectrum. Slightly annoying, but not totally objectionable.