It took me at least 5 years to find 2 NOS Mirrors in metal.
Problem is, there are not many around and secondly, you are
up against restorers of high end Ferrari and other Italian exotica,
with very large budgets. I saw a pair, not even NOS go for
USD $ 1,800.00 earlier this year.
Then of course there is the problem of getting 2 with the same glass tint, or non at all.
But keep looking & good luck.
They are out there.
The last NOS pair that I got were on eBay Italy for not much more than the plastic versions.
There was also a similar metal mirror made by Alexander Accessories in the UK during the 60's-70's which are slightly larger and more suited to the resticted vision on a 40.
These were die-cast and chromed and of lesser quality but still nice nevertheless if you can find a clean pair.