It would make a nice treatment for the frame but there are better solutions for the "glass" part.
I have a set of 84 sail panels that I have been hanging on to, they have actual glass and not plastic.http://www.fierosails.com
has replacement sail panels
If you just want to make what you have now look better then John is correct you can use some body filler in the crack.
Used parts are getting harder to find and we are all having to think out of the box to keep our cars on the road.