I completely missed the numbers 25 & 26 in your second post. I remember having a spare #25, it wasn’t in great shape, but can look for it at the weekend.
No doubt some of the Italian Lancia specialists/breakers may have them, I would try
http://www.classiclancia.com/ - remakes a lot of trim
https://www.oldlanciaspares.com/ - Cavalitto
http://lancia.co.za/- breaks old lancias
But the other problem is shipping to the UK. The another option is to make it using a bead roller, although it would be a lot easier in aluminium than stainless, Maybe go down that route and keep a lookout for some original stainless ones, as these items do come up now and again. It would be a shame to keep the car of the road, just because of this.