The bar is natural, zinc plated; the brackets (obscured by the heater tap) are satin black but the 2 bolts and spacer washer on engine end (just visible) are also zinc.

Here is the better quality scan for you. The lack of washer bottle is a little puzzling!

I have just had a small tin of metallic green mixed at a local Motospray outlet. They included the formula, which is in their Auto Enamel line.
I don't know if NZ has Motospray brand - it was owned by Hi-Chem and now by Rustoleum, which is in NZ.
But the formula for this colour can't be used with a different brand.
The engine green metallic is very, very, very similar to an old 1970s Chrysler/Mitsubishi(Aust) colour called Sherwood Green (Met.) which might be easier to track down.
It looks like this.

Hi Bill B

Thanks for your info and I will look into Rustoleum.

I have looked at an Australian BMC Paint colour chart in the last few day's and found Metallic green Metallic in the trim colours.
1967 show's this colour under Duco with a code of 10489.
The next time Metallic Green appear's is 1971-72 under trim colour and is also Duco with code 13357.
The trim colour chart also show's Silver Birch and Silver Ash which I understand is the wheel rim colour's.
Working on these codes to see what might turn out for a colour match.
Interesting project

Cheers