WE are working on a Billet steering arm / bump steer kit that will hopefully solve this issue.
it will use a 5/8 heim outer and a long ti e rod sleeve.
the problem is. we can only move the steering arm so much. and there is alot of different rim profiles. PLUS as you increase the back space the rim gets smaller ID. also you need to realize that the Sway bar becomes the limiting factor on the back space.
with a stock sub an stock (replacement) sway bar i would be surprized if you could fit much more than 5.5 bs wheel on there.
there really is only so much you can do.

Something about 5 lb of S%$t in a 2 lb bag.

I had a similar problem installing a washer between the spindle and steering arm
solved my problem.

The Z-28 steering arms are #3902519 LH, #3902520 RH and shorter in length. If you can find them they're pricey.

I had to spend about 6 months of constantly checking eBay before I found a set for myself, didn't even find them by searching part number (listed as "Camaro z28 steering" or something like that instead) but I was able to zoom in on one of the pixelated pictures and read the part number on one of the arms.

I have the Z28 short steering arms. They came with the car :-)

I solved the problem by adding a 1/2" spacer between the spindle and the steering arm.
Also the rotor hat is 1/4" thick and that gives me extra space.
So I am fine now :drive:

I may have a set of the SHORT LH-3902519 RH-3902520 turn stop pad is more pronounced on top. I am running a speedtech pro touring subframe with the rack and pinion that requires the unisteer arms. I had someone else interested but they are not sold yet.