Ok, I just got the coil springs for my Darrin from Deaver Suspension @ 902 E. 2nd Street, Santa Ana, CA 92701. Talk with Scott Born 714-542-3703.
I paid $325 for the springs plus the $25.19 shipping from where they make them. Very reasonable from some of the other places I talked with. Scott took one of my Darrin springs and took all the measurements then sent those measurement off to be made, it took about 6 weeks.
Here is something about them: Originated in 1892, Deaver Spring, Inc. (formerly known as Deaver Spring Manufacturing Company) specializes in suspension work on cars, trucks, 4×4’s and Recreational Vehicles, which is to say anything with a suspension.