Hi Leonard,
Thank you very much for your help.
My car is a US late 1970 model, with the high/low beam switching on the floor, and the wires I am talking about are those inside the chrome lever (see picture attached), connecting the handle to the contact plate.
The originals are +/- 1.3mm in diameter, so probably AWG 16.
My concern was about thickness, once normal Awg16 do not fit inside the chrome lever (it's very narrow).
Also, my diagram is slightly different from yours and do not carry info on wire colors and gauge.
So I am going for the awg16 as per your recommendation. With a thinner cover.
Many thanks
Francisco