Another option, Dan, might be to have a local automotive upholstery shop rebuild your seat. Many different foam density materials are available. Some shops will use two different density layers under the cover.
Sending your seat to Corbin for a rebuild will be pricey. I have one on my Tri Trophy that ultimately was rebuilt locally. Plus, you may not be able to select the padding as you might with a local shop as emailing descriptions of how your fanny will feel might not be practical. Kinda like Forrest Gump, "... you never know what you're gonna get."
Welcome to the forum!