There was an episode of Wheeler Dealers where they had an ‘81 SC fitted with a new heated windscreen at Evans Motorsport
https://mikebrewermotoring.com/news/wheeler-dealer/wheeler-dealers-bags-a-porsche-project/
Very nice and worthwhile upgrade for 3 or 4 season owners as we all know how dismal the defrost fan clears the inside.
When I seen this I hoped by now someone in the US would have imported a boatload.
If you have a streaming service (Season 18 Ep.2) they show a bit of info on having it wired, the short youtube video doesn’t show the windscreen update.
https://youtu.be/IzdwOf3fEn8