I am not going to bother digging out the OE SBC z bar in my shed because I can't lift the crate it's in while on crutches. But 100% it has a pivot on frame side.
Look at HB City SBC z bar. Pivot on frame side. I trust their part over Ricks/Eckler import crap.
http://www.heartbeatcitycamaro.com/store/product/17649/Clutch-bellcrank-all-SB/
Look at Year One SBC z bar. Pivot on frame side.
https://www.yearone.com/Product/1967-81-camaro/ru1806
I would almost bet that the "fixed" SBC bar end in your pic is just a shipping plug not removed for the photo.
I wish you would stop with the misinfo on BBC installs, but I guess I am doomed to refight the battles as they come up. If a BBC bar was crooked like you say, it would not fit in the same space that the SBC bar does.
It would also be likely to bind; think about what you keep saying. Are the upper and lower linkage holes on BBC unit drilled perpendicular, or at an angle? Every piece that attaches (upper clutch rod, lower swivel for SBC, lower rod for BBC) all go through holes at 90 degree angle and get a simple pin to secure. Are the arms off the tube twisted to allow these components to connect this way? NO!
Both z bars mount the same way; the BBC z bar installed on a correctly installed BBC is not visibly cocked forward. It is same alignment as SBC and L6 bars.
If you can't read the Year One and HBC descriptions and realize you are wrong and don't replace your above image with the shipping plug installed to keep the frame side pivot ball stud in place on the ride over in a giant container ship, well then I give up.