Take a look at these. Both are triangulated 4links which is similar to that used on the Chevelle A-body.
Art Morrison:
http://artmorrison.com/homepage.html
Chris Alston Chassisworks:
https://www.cachassisworks.com/cac_gBar.html
I installed the Chassisworks G-Link in my 68Camaro just like Ed's above and I'm very happy with the results and ease of installation. I notice on the Chris Alston web site they now have some additional products for these suspensions that I may have to think about.