That's a VERY interesting window regulator mechanism! If there's a lack of material to put on the door sill for the window, you can always go to the craft store and get some similar type felt, cut it to size, and then attach it with an epoxy type glue in a small amount.
My only hope is the windows travel to the top of the door posts. In pics I've seen with the windows up, they don't seem to be up "all the way".
An uptop would have been nice too, but I can scratchbuild that if need be.
BTW, I've done working windows on much smaller models. However, I've used a different setup than whatβs showing.