[Rick 427 Cobra]

Proper gauge material! Now you really have my attention. This is one of the things that McCluskey mentioned when I called him. He was talking about going to England for springs. That's key to spring rate. Properly tapered and end treatment?
Do you have any drawings for a rear? My drawing calls out 41.5" c/c, spring " flat". 40" c/c with 4.75" c/l to bottom spring relaxed.
All leaves .219 with a taper to .156 at the ends. 7 springs total.
Alcan's price sounds good for the correct spring.