Hey,here I am.I did the swap once because I had a 51 that needed a door and I had a nice 50 door.
A few holes need to be drilled for the different 50 window regulator,a small notch needs to be cut to clear the vent window arm.And maybe a bracket needs to fabbed up,it was 10 years ago,the small details are a little foggy.Anyways,it was easy to do with common hand tools ,just compare doors to see what needs to be done.