I've been considering this too,the webbing dampers in my springs dissolved long ago,sometimes it's like being in a kids bouncy castle when i'm driving!

Apparently the different foam colours denotes the density,there was a fella on the HAMB A.D. Truckers social group did this,he replicated the factory seat to the point he could still use an aftermarket stock replacement upholstery kit from I think it was LMC.
When finished it looked pretty stock but without the drawback of tired,broken springs.

I'll see if I can find the link.
Edit: Here you go,it's not as comprehensive as I first thought but go to page 6 and you'll get some idea,it seems fairly straight forward but you might want to invest in an electric carving knife as it seems to be the weapon of choice for carving the basic shape,then switch to rol-loc discs on a die grinder for final shaping
I hope this helps.
It's actually an awesome build,worth the long read..... grin

http://www.jalopyjournal.com/forum/threads/my-53-chevy-truck-project.629357/

Last edited by jockbolter50; 02/19/2017 8:27 AM.
1950 Chevy Advance Design 3100 in Scotland
In the Stovebolt Gallery
More pix on Flickr.
I've definately got this truck thing in my blood ... my DNA sequence has torque settings
"Of all the small nations of this earth,perhaps only the ancient Greeks surpass the Scots in their contribution to mankind" Winston Churchill.