[JC455]

On my old 68 LeMans, I used Hotchkis 1" lowering springs front and rear. I've used their springs on several of my cars, so I know their ride type- taut but smooth... more BMW than the factory wallowing pig ride. This is what I like, so their product suits me.
I used a T/A 1-1/4" front bar and a 1" rear aftermarket bar.
Rebuilt all the suspension w/ rubber bushing and new everything, including some decent mid-range shocks. I ran Centerline AutoDrag rims w/ 235 60/15 F and 245 60/15 R.
The car rode like a modern sport sedan AND, most importantly, it no longer scraped the headers on every RR crossing or dip in the road.

On my 64 Tempest I'm currently throwing money at, I decided to go "big", so I used Hotchkis 2" drop springs in the rear along with the factory worn-out 6 cylinder springs that now support a Poncho V8. It looks cool as cool gets... ride poorly due to the 6 cyl springs.
After investigating the clearances of the wheel wells, the 2" rear is probably gonna be a touch too much if I have any weight back there (even small passengers), so I bought some Global West 1" spring risers for the rear.
On the front, I purchased some Hotchkis 1" lowering springs. I did this for several reasons:
1) Since I don't know what 'stock' is, starting with a 1" lowering spring will give me a solid base to work from because the 6 cyl springs are SLAMMED.
2) When I eventually install the SPC lower control arms, they have a built-in 1" drop pocket, so I'm able to potentially lower it 2", If I don't use the spacers that come with the arms.
3) If I choose to mix and match things, I could potentially end up with drop spindles. Again, this opens up options for playing with spacers to fine tune the amount of drop.
A lot of people like drop spindles because you can use a taller spring and still lower your car. If the spring rate is correct, you can get full travel and a softer ride. Again, I prefer a slightly firmer, sport sedan feel to my cars.
I won't know the final stance until I get there, but I like options.
I'm running 245 45/18's on 18x8.5 Vision Torque rims on all four corners due to the small wheel wells in 64/65. They have a 5.15" backspacing that you might benefit from too.