Aluminum vs cast iron cylinder head suspension effects

It's not enough of a difference that you'll feel unless you push your car to the limits and even then it's still not much. Upgraded suspension will make far more of an improvement. When I went from iron to aluminum headed 360 in my Duster I think I had to adjust the front ride height down by like 1/4-1/2" with 1" torsion bars (at the time, now running 1.14" bars) but the car felt the same in normal driving. The real trick is to move the weight to the rear more than just removing it from the front.