How to paint 1958 Treadle Vac brake booster and master cylinder?

[www.eldorado-seville.com]

I'm in the process of rebuilding the Bendix master cylinder and booster of my 58 Seville.
During the rebuild my once great looking unit suffered a lot due to the brake fluid that damaged some of the paint.

I decided to wire brush all the paint off and repaint it again to make everything look as perfect as it did before.

Can anybody confirm how it should be painted?

- Booster satin gloss black or glossy black? I think it should be satin gloss?
- Master cylinder cast metal grey? ( I think it was left natural from the factory but I would paint it in a grey that comes very close)
- Master cylinder reservoir cover (screwed in with 4 screws) - bare metal grey or black? (had it black before, but I'm not sure if it is correct?)
- Master cylinder cover plug - cast metal grey - polished?

Thanks for your feedback! I want to make it 100% correct again. I have removed all the paint today and I'm waiting for some Eastwood paints to arrive. Everything is in bare metal and cleaned now and disassembled. I have rebuilt all internal parts and would like it to look new on the outside as well.
Here is a picture of how I had it painted before - I think I had it correct last time? Just not sure if the reservoir cover was correct in black...


all the best,
Gerald