Repair of the broken No. 9

@Camp numao pardon a dumb question from a friend but I've seen people line gas tanks with a smaller tank inside using the outer tank just for looks and a brass tank to actually hold the fuel on the inside. Would a smaller tank be able to be fit into the cracked original tank?
Not that I've done it but I've seen it in really old motorcycle types that had two halves of a fuel tank have a large seam leak. To keep it looking original they basically cut the tank halves apart and had a 3d metal printed tank to install inside it... Maybe you can do something like that. There's a bunch of bike shops in your area who might know who can make you a special tank you can work with out of brass?

 

I think you'd do a great job of it. But best of luck with whichever repair option you take, what a fantastic project to be working on!

 

Its do-able, its even worth having a go regardless to hone your skills!

Thoroughly anneal the brass sheet and make it longer than you need on the overlap, that way you can gently roll it past the end point so you get a nice continuous radius rather than a line/mark where the very end steps off.
Do you have a friend who does woodturning? They would be able to roll you a cylinder of the correct diameter to use as a former (or slighly undersize to allow for spring-back, then use a shim/card for sizing it to the finished diameter for soldering), brass is very forgiving when its soft.

If you are nickel plating it afterwards, you could even substitute copper (in a shade heavier gauge) sheet for ultimate workability.

Good luck with the repair, I'm sure it'll be fine.
Alec.