In the title, you're talking about 78 & 73 and in your topic 78 & 72, is it a 72 or 73 ?
Have you checked the stamps on the harp on each ?
The best answer I can give is actually a question : Have you tried the pianos ?
If yes, what's your favorite ?
For sure the 72 seems to be in bad shape, but sometimes, visually it's bad, but sonically it's very good.
I owned 4 Rhodes in my life, 74, 77, 78, 72, I still have my 77 and 72, and I prefer the 72, but it's my personal opinion... The 2 are perfectly adjusted, so it's easy to make an opinion. But in your case, maybe the 72 doesn't sound as it should...
Another thing, 72's are more rare, so usually more rated, and for me of better overall quality...
You really have to test them, because a 78 could be an excellent piano and a 72 a bad one.
I disliked my 78, hated my 74, really really like my 77, love my 72 Buz Watson.
I hope I helped you
G