You MIGHT be able to convert the early doors to fit vent windows into them, but there's some brackets and other things that would need to be installed inside that would be difficult without removing the door skin. You'd also need to get the correct interior window molding. And I'm not sure that the window regulator mounting holes are the same (the regulators are definitely different.)
An easier approach would be to get 52-54 doors with pushbutton handles and install the correct latch strickers on the door pillar to match the different latches.
If your original doors just need patching on the lower portion, I would do that. Mine were not rusted on the outer part, but needed patching on the bottom inside. Patch panels for those weren't that expensive, and fit pretty well.
