Current XK120 colours

Possibly. The car listed with that current colour - 679661 - doesn’t include an entry under original colour so possibly, even likely, was changed.

I like Pastel Green Metallic but would prefer silver, both ostensibly not offered for the 1954 model year. Then again, no metallics were standard offerings from December 1952 to August 1954, though there was this from Rob Reilly in another recent thread:

This xkdata entry, for a 1954 XK120SE OTS whose chassis number precedes mine by 26 cars, is interesting

It lists Silver as the original colour, gold as the new one. Also mentioned is the availability of a JDHT certificate for the car but there’s no scan of the certificate so likely an error.