Here's a company that was making valves and/or springs for the triples. I don't know if they still are - the catalog PDF was taking me forever to open so I leave it up to you. I don't know how the prices compare to stock speed 3 parts. I still had the link from when I built up my Tbird a few years ago.

Stewart ....... "It's outside your field of expertise." "Poppycock normally is."