Zafira rear drum backing plate replacement

[Opelman]

I have an Opel Zafira year 2000 which I ordered and owned from new. It was ordered from Holland with all the options available at the time and is still a very nice reliable car.

The problem I have is it's a 1.6L with Brake drums on the back. You seem to be able to get all the replacement parts except the back plate that holds the piston and shoe assembly.

This is very rusty and at a point where I would not like to do an emergency stop as large metal flakes are dropping off every time you touch it.

Where can I get two replacements, as I have been told by all parts and factors company's that they are obsolete.

Can you still get them? Or can the rear be easily converted to discs? I do not want to scrap this wonderful one of a kind car.

I have a spare Zafira axle with discs and callipers attached, but I assume there is a brake pressure regulator, and the hand brake cable that needs changing.

Help.

Thanks