Gosh! You don't find those very often, nowadays. Prior to the introduction of "modern" bullets, they were my go-to bullets in 7mm. I've taken more game with them than all my other bullets combined.......deer, elk, bears, etc.
I've heard the BTs were a replacement for the SolidBases, but comparison of recovered bullets tell me they were not the same.
I managed to find a big stash of .284 140s and 162s on this site, several years ago. At the time, he had them in numerous calibers, if I can find his username, I'll PM you his contact number. Good luck in your search.