targa door differences

Hi,

I have some rust at the bottom of my passenger door. My body guy would prefer to replace the door than fix it. Besides to side impact beam, what are the differences between a '72-'73 door and a later door. What door can I install without it being noticeably different from the correct door?

Lastly, aside from the window frames, are there any differences between a coupe and a targa door shell?

Thanks again!!!

I'm using 71 Targa doors on my '71 S coupe. As far as I can tell, the door shell is exactly the same.