I'm aware of the chromed plastic but don't know of a place that does it or that I would trust to do it.
I have experience with Muggy Welding and it is perfect for pot metal. I don't have firsthand knowledge of a Muggy repair being chrome plated but Muggy claims that it can be chrome plated if the repair was made with Alloy 1 low temp solder.
By the time you go through all of that expense and rigmarole however, you may as well just cough up the dough for one of the reproduction hood ornaments.