Is the opening of the window curved or not?
You don't need to go by what they had in the Streetbeast plans, yo can make anything you want to work. A straight line from top to bottom on the channels is number one. It can be leaning but it needs to be straight. Make these channels then make a template out of card board that fits in there and slides up and down these channels into position then back into the door. Then using that template make one from 1/4" tempered masonite. This will represent a piece of glass perfectly so if there is something cockeyed about your channel you will know because it won't go up and down freely.
Once you have that you get a regulator and mount it so it pulls your "window" up and down. This could be a factory regulator out of a car which these days have gotten so small it may be a way to go, sorry I have no suggestions on which one. But these days there are all kids of them that aren't a "scissor" like regulator but a very simple cable operated one. You mount it in a vertical position in the middle of the door and it is self contained without any other channels or anything and it pulls the glass up and down using cables.
But this isn't a big deal if you take one step at a time. First things first, make up a template and see if the channels you have in there will work.