On my 69, I run a 3.5" Wild Horses suspension lift, a 2" body lift, and 35's.
I run duff's t-rex arms, 7 degree bushings, and a hellwig anti sway bar.
I run the thing down the freeway at 70-80 no problem.
No, I don't think I would want to go lower (or higher). I like it right where it's at...