Thank you very much for the information.
You have very kindly put my mind at rest regarding the top or bottom. As I have to drive over so many humps these days, the bottom is unlikely to work out well. The ad/disadvantages made me think.
I have a couple of holes behind the bumper so can mount the number plate on the 2 metal stays. My thoughts are not for a additional brake light as it was not standard on the 1967s. Hopefully I will still be noticed ..........
A pleasant week to you all.
Warmest regards,
Stephen