[Superman]

Dear, this is a good question with which to illustrate the importance of the advice you've received. This problem will absolutely, positively require that the windshield and trim be removed. When you are ready to place the glass back in, it won't make sense to re-use the old glass and certainly not the old seal. But first........

When the glass and seal are removed, you will find out the extent of the rust damage. The body of this car is sheet metal. You know that. Sheet metal is fairly thin. You know that. The metal windshield frame into which the glass is set is sheet metal. The sheet metal is formed into a sort of 'saddle' that the glass and seal slip into. The bottom of that opening, at the cowling.......where water has been accumulating periodically over the past thirty-four years......will not be "pretty." It most likely will need to be rewelded. Into the shape it was when it was new. The easiest way to do this would be to find a donor car and cut the windshield "saddle" out of that, and cut the rusted one out of this car, and weld the donor piece in. The entire dash will need to be removed for this operation.

This is just one of the surprises you would encounter if you bought this car. It would be cheaper and easier to buy a bare tub and build a 911 out of spare parts (using purple paint when the time comes of course) than to restore this car.