So you need someone who can weld this, which shouldn't be all that hard to find (what were they made of in 72). Then when the welding is done they need to own, or you need to go to someone who has expensive tap/reamers, and doesn't mind running them through a weld. And they need to have the tools to do a French BB. So you are looking for an expert tig welder with a passion for French lugged bikes... Who works cheap... And doesn't know what expensive tap/reamers are supposed to be used for...

Realistically...