2nd gen horse collar seats ??
 

Getting ready to restore a set of 2nd gen deluxe horse collar seats. And have a few questions.

Who makes the best seat buns?

Does anyone make the lower back panel ?

The bottom seat springs are available. But I need some of the springs that attach them to the seat frame. Does anyone make them or what is a good substitute ??

Thanks in advance for any and all advice for this project.