Being that Conn owns Blessing this is a plausible scenario.
I really like this horn, in silver plate, and have maintained it in like new condition since new.
If you want a stock pipe you can use a repair department near you and they can order stock Bach parts.
I found this info a little disconcerting because I assumed the TR300's were built by Bach in the the Conn Selmer plant.
It's starting to look like the low end Bach horns are either the same as or share many parts with Blessing student horns, at least before the Conn-Selmer strike.
As far as your horn it depends on what you want to do with it.
If you want custom lead pipe to spruce it to make it play better I suggest a lead pipe by Charlie Melk (Charlie's Brassworks in Milwaukee) or Cliff Blackburn (Blackburn Trumpets in Decatur Tennessee).