It's all fabbing. The channel for the window should be about a half an inch tall, the glass is about a quarter and then the urethane bed would be about a quarter. Do some testing on smaller pieces before you jump into it. The base of the channel should be about 3/4" to make the urethane bed wide enough. Now, you could go with an, 80's S-10 style rubber moulding around the glass that simply is T shaped and sticks between the glass and the channel into the urethane.
Windshield Glass | 1982-93 Chevrolet S101983-94 Chevrolet Blazer1982-93 GMC S15 Sonoma1983-94 GMC Jimmy | LMC Truck
But if you do this the urethane bed under the glass would be seen thru the glass. So you would need to put a "frit" around the outer edge (the black edge around glass on late model cars) to hide the urethane under the glass. The wider one (number 3) may be wide enough to cover the urethane, and you won't need the frit, you will need to do some home work on that one.
Or you could make a moulding out of a T shaped metal tacking a strip under a piece of 1/8" by 3/4 inch or so wide metal. You then round the corners of the metal along the edge and chrome plate it. It could be stuck in there the same way as the S-10s style. I am thinking this could be done (never did it) but cutting the glass out later could prove to be difficult!
Let's see if anyone else has any ideas. There are of course other "T" mouldings you could use that are larger.