A 406 should have either
These:
https://www.les-six-troenes.com/part...t-beauty-rims/
or
these:
https://www.les-six-troenes.com/part/16/marchal-105160-headlight-beauty-rim/
These are both in the Marchal 1959 catalogue, the ref 7966 is the earlier model 105.160 the is the successor
The Marchal units used at the time in the Bristol cars are slightly larger than 7, and the rims linked to above only fit the Marchal buckets.
Helping keep the cost down is the fact that the rims were also used on Ferrari 250 swb cars.
On my 406 I fitted p700 lights into generic buckets, I had to do a tiny bit of filing and possibly a new hole or two, but certainly nothing major, and nothing that would prevent original parts being fitted should they appear/I win the lottery. the trickiest part was finding trim rings that filled out to the edge of the wing. I tried all sorts and in the end the best I found are from a Volvo 1800s, see pic.
hth