Scaling a stock suspension car.

If you think about new sprAngs, I would not get the MP SS sprAngs. Call Mancini and actually TALK to them. Tell them what you have and that you don't want the MP springs, but some of their sprAngs. They will fix you up. I say that because the MP sprAngs are made in Mexico and the metallurgy is not consistent at all.
I put the Mancini XHD springs on my 70' Dart (not a race car) years ago and can say they are very good quality if nothing has changed since then.