We run in the 9's with our 505 with Calvert springs and bars!
4 link is complicated and tough for us to tune. Also, fragile if
you do any street driving and make sudden turns1
I agree , Not a big fan of 4 links , I have modified spring set to work far better using more 1/2 leafs forward & strapping them tight with clamps at the front .
The best system I have used is floating leafs with traction bars , I would have trouble spinning the tires in the rain & could lift the front tires on the street easily .
If a good quality 4 link is installed and tuned properly, they make those old cars ride pretty well. It’s all in the installation, and alignment. Get it right, and you’ll be happy.