I'm sure your cars all look fantastic, but when I chopped my '53 Chevy and laid down the rear window at the same angle as the beltline trim the '50 Ford back glass I have was too round and humped in the middle. I worked against the lines of the car instead of with them. And the only one I ever saw in person looked wrong for the same reason. Just sayin... I'm sure the angle of the laydown makes a big difference. For my chop a '48 Chevy window was near perfect.
1949 dodge rear glass can work,it's less than an inch different than the 49 Chevy glass used in these chops. There is one for sale on hamb marketplace
I used a 46 ford sedan rear window http://i1273.photobucket.c om/albums/y406/raysnewbucket/IMG_20140922_035237_zpslbfq9xuf.jpg