rust in firewall, dodge phoenix/plymouth fury

Hiya people.

Years back I bought an Australian Valiant Charger which had the wiper motor
mounting plate in the engine bay rusted out. A few years later my wife
bought one too - that too had the plate rusted through..

Well I've just bought myself a 1970 Aussie Dodge Phoenix ( a rebadged
plymouth fury) and yes, it too has the same plate rusted through - I've had
to weld them up in the past but I'd really like to do a decent job of
resoring this car.

Does anyone know if these panels are available anywhere, aftermarket or old
stock?

After all the Val's I've seen here in australia seem to have the same
issues, I'd half expect someone would make an aftermarket replacement panel

thanks

karl