I had to use a couple of seats to actually make a good set of bones and springs.
I ordered my Briar Brown seat cover from Raybucks and did the seat work-up using some dense padding from Walmart to top the springs ( Carpet is a good idea) and some softer egg-crate type foam as well.
I used hay bail twine to help secure the top foam layers while installing the cover.
So far, no complaints and the seat looks good and is comfortable.
It has that twangy spring sound from the action of sitting on it but for me, that just adds character to my old truck.
Years from now maybe, someone who might remove the cover will find a message left from me on the padding!