According to my Dulux Autocolour book Araluen Blue is code 09599. It is also shown as a FORD fleet colour- code EY421. This may help to get the right colour.
The metal door check strap, only on the drivers door, was a period accessory to replace the door check strap. These broke regularly so the metal wire check strap was popular.
The ID plate is from an early OZ built 850 but the number stamped on the firewall and the ID plate don't match so who knows what it actually is.
The ID plate is usually fixed to the firewall behind the clutch master cylinder with the car number stamped below the plate. Maybe early cars had the plate and number in a different position.
Check the top of the radiator surround panel to see if ther are any codes or numbers stamped there. This may give some clues.
The wheel trims were also a period accessory to make it look like a Cooper. The Cooper trims were all one piece though with the hub cap and trim combined.
Early cars pre 63 had the vinyl kick panels. My 63 850 had the all metal ones.

Ooops! Posted this in both categories.
Hope this helps.
RonR