I love the old "Classic" trucks
Unfortunately they are prone to a little more wind noise.
The vent window (wing) seals are not bad to do. Just take your time though.
The window has to come out then the seal can be replaced then the window goes back in.

The 91 Burb I had last winter was the most quiet of any of the classics I have owned but I dont think anyone ever opened the wings and I did not either.
I have seen some plastic fairings the install all around the top and front of both the wing and the roll up. These probably will help stop some of the noise.

As much as I like the older trucks, the 95 dually is so quiet inside. The only downside on the newer styles is if you want to open a window a bit when your going the wind just rumbles and buffets something awefull.
The plastic vent shades also stop the rain from running in too.

Good luck with your classic ride

Robyn