Very nice.
Looks just like my '72 144E. I had to send it to the scrapyard a few years ago. Still miss it.
I noticed yours has the flush door handles like a '72.
Fender mirrors, plate and lack of side markers say it's not a NA vehicle.

Edit: Tried posting a photo of my car the same way I've done it for years. For some reason it won't come up.

Edit 2: Hey! I got it!

I'd also try adjusting the valves for the clatter. You probably realize already though that these cars really are not very quiet on the highway.

As for the windshield rust. You may want to pull off the trim and clean out the gunk that has accumulated under there over the years and then see how it looks. Maybe it is just some surface rust and you can get a few more years out of it. It can't hurt. My personal opinion of filling the crack with silicon or caulk is that it will make things worse by trapping the existing moisture inside there. Be careful when pulling the trim too. It is possible that the clips holding the trim could be rusted as well.

Best of luck with your car.

--
'60 PV544, '68 220, '70 145, '86 745T