Still not sure if you only broke the main spring or are needing others but this is what I found in my yard.
It's the main spring from my '72 J2000, it has the bronze bushings typical of that era.
It measures 50 3/4", eye to eye, all by itself with no weight on it.
The rear bushing has a 7/8" ID.
The front bushing has a 1" ID.
The front bushing is worn all the way through to the spring but just in that one area, spring looks untouched.
I'm not sure if those bushings are available or if that is even what you have, I could ship it to you FedEx for the cost of shipping and some beer time and tape. It probably would not be that bad for just the one spring.
I do have intact the entire other spring pack, it's very heavy and I doubt it's worth the cost of shipping but I could look up a price if you think it would work for you. Front bushing is in the same condition.