Repairs on old Eb (Marlin/Martin)?

[Tigertuba]

I have recently got an old Eb 3valve tuba. I can't read the name clearly but it is either Marlin or Martin does anyone know for sure?
Also, the lead pipe is broken near the bell, I am wanting to form a new leadpipe and solder it on. The horn is silver and I'm not sure if this is possible for me to do. Is a specific type of solder used? Will the tuba blue is it is too hot?
I have also thought of maybe adding a 4th valve down the line, is this more of a hassle than its worth?
Any suggestions on what to do with this old treasure? It plays well (when putting to sections of leadpipe together) and I would really like to use it someday! Thanks for all your future suggestions!