We put a set of aerostar springs in my buddie's '58 Edsel and got about 3 inches of drop. I think that is about what most guys are getting out of them too.
I used the MOOG CC850 (about $75.00 pair) on my 51 Ford Shoebox, and it was at least 2"-3". No problems. (But I did get whole front suspension rebuilt at same time.) Would never heat springs again.
In most cases you will get 2 1/2" after some driving it will settle another 1/2",the other plus is an improvement in ride and cornering.The listings for the matching shocks is in the 52-59 Ford "sticky FAQ."
You will need spacers if you run the grenada spindles and a big block. With the Grenada spindles, the Aerostar springs put the car too low. I like it too low, but it wasn't drive-able. I'm going to take a bunch of weight out of the front (re-locate battery, and aluminum heads on the big block), and also put a shim in the springs and keep running the Aerostar springs. I want it to be as low as possible and still drive-able. Here's a pic of the springs uncompressed next to each other. Big difference.