Edit -

Believe the rears were new overload coils, the fronts were for the Buick.

Front
https://www.moog-suspension-parts.com/moog-cc653
And I think I did cut a coil off of them.

Think the rears might be overload coils.

Interesting, do you know the free length and/or spring rate? Which end would you remove a coil from?

https://www.summitracing.com/parts/EIB-12003000300S

I think this is what I used in the rear. They fit the rear with out modification to anything, and I thought the ride height and rate worked well. The fronts I paired them with were also from Eibach and I think were a 13"x5" 250 lbs spring. Those required new lower spring perches be made.

According to the Moog site:

part number moog-cc653
Both ends Squared
Resting height 13.44in
installed height 10in
inner diameter 4.25in
wire thickness 0.64in
spring rate 357#
Load 1230#
Spring Type Variable Rate