Hi Shane & Michael, thank you very much for replies.
First off, i didn’t know that ProRes 422 would suffice for the footage from the 1D. I understand that it isn’t FULL 4K, but rather a more compressed version of it, but, still is 4K resolution.
Secondly, I did choose a few edited clips from my timeline and converted the ProRes4444 clips to 25fps and replaced them with the original proxy clips.
I had to reduce each of the image clips by 50% so that the full image was shown (was zoomed in otherwise), as well as render, but it all worked out and played back fine in my timeline.
I’m actually quite impressed, as I thought that i wouldn’t be able to have a work around in FCP7 to work with this 4K footage.
So far so good.