Hello!
I don´t undertand about leadpipe too much! Sorry. But in your situation, I think it is not good to play bass trombone with a silver leadpipe, because I think your sound will be too much dark (like euphonium). If you normaly play tenor, I recomaned the more open and easy leadpipe for bass to make easier and clear sound. Do you understand? For people that normaly not play bass it is dangerous that the sound with bass it will be too much "gua-gua" and dark.
Only it is my opinion, maybe it is not the best!