Most everyone has forgotten one of the first sentences in your question.
It reads: " Is it a task feasible for the DIYI body novice that has welding skills?"

The answer is NO! It is far beyond most professional bodymen (as if you could find one of those).

Most of the early car chops had at least one pillar vertical. That made the usually back pillar easy, relatively speaking. The windshield usually had some rake and that was sometimes made up for by stretching the roof.

Windshields in early cars were flat plane and it wasn't that hard to get them made. I must have missed the part about using another car's windshield. Maybe I was just fixated on real hotrods, '48 and older.

On a later model car where the A pillar tilts back, the C pillar tilts forward, and the roof has a significant tumblehome, it becomes more than 10 times harder.

Don't do it.

R.