Unless someone knows of a better way, I will be making a template from luan plywood and taking it to a custom glass shop to have the window made since these windows are not stocked. I borrowed Wilkinson's cardboard template for a tall window and it found it to be a poor fit on my car. My hunch is that each one of the back window openings on the early cars is a little different.
I am trying to figure out how much of a gap between the glass and metal ridge is tolerable. I know that a bigger gap makes the installation easier. But if the gap is too large then the glass could wobble in the gasket or even come out.
Any insight on this matter is appreciated.