which chevy springs for rear inboard?

[Xtremeworkz]

Hey guys..about to chop section and inboard rear springs on my j10... want to maximize my flex and need to know what year? make? and model to get the rear springs out of...looking to get a set asap...any help is great ..

63"

also what is the length from the perch pin to the spring hole length on the 63" and 59"?

[Elliott]

I pulled two sets off of '90s trucks.