I recently replaced my rear leafs with the "standard" ones from this site:
http://www.stengelbros.net/AMC-Eagle-Leaf-Springs_c_438.htmlThey show the Eagle leafs as 23x29, so a little different than the ones you mentioned. I think the 23" dimension is from the front to the axle mount, so the Ford ones would push your axle back by 7/8". You might get away with this with stock size tires, but the driveshaft, brake lines, shock mounts, etc would all be affected. Not work the risk for me, but you may decide otherwise.
Also, what is the arch dimension for the Ford springs? Eagles are pretty flat.
If your stock leafs are in good shape, consider adding a helper leaf from a Jeep Cherokee to get a little lift. I added a full length Cherokee helper spring and combined with the new rear spring pack I got a 2" lift in the back. They also make half length helpers if you don't need quite that much. I got mine from Iron Rock Offroad but there are several Cherokee kits out there for less than $100.
I was just planning to add the helper to my stock springs but once I got under there I found a snapped eye on one main leaf. I ended up with a bunch of spare bushings since the new springs came with pre-installed stuff. I may have some parts available if you are interested.