David,
I got a set of sun visors for Christmas which came from Melvyn Rutter, I believe. They are a smoked plexiglass material and have sufficient cut out to go past the large stainless interior mirror from Heart of England which I also got!!!
The top frame of my windscreen had posts built in and the visors just screwed in - no modification whatever needed. I find them particularly good in low sunshine - you can look through them like good sunglasses!
Cheers!
