Years ago over on Team Camaro there was a guy that made/sold rear leaf springs that had a 2nd leaf under the main leaf that wrapped around the front main leafs spring eye.
I think his name was/is Chicane??
My 1st Gen 350SS Camaro has JCW's '68/'74 Nova 3-leaf mono replacement springs under it with a couple of stock firebird 5 leaf spring leaves that are 2nd and 3rd from the main leaf. It's been years..
I still have to tune everything if I ever get off my stupid lazy as*!! Car's been sitting in my garage since '87!!
Shocks, Springs, Brakes, Frame, Body Work, etc