67-72 c30 lowering question

[91rcsb]

Hello,
I have currently dropped my c30 by cutting 1 coil in the front. This still has it sitting a bit high after flipping the rear axle. I was wondering if any one had info in regards to the differences between the c10 and c30 coil springs. My current ground to fender height measurement is 30 3/4" with a 225/75/16 tire and I am about 1" from my lower bump stop making contact. I am looking for another inch. Considering c10 2" or 3" drop springs if they will net me a bit more drop. It seems most fender height measurements posted on the forum by c10 guys have been close to mine before they dropped. Retaining the 1 ton suspension specs is not a concern. A front disc swap to allow drop spindles isn't in the plans for this low budget project.
Thanks!