Large img file when mounted doesn't have any contents

So, I killed my backup when rsyncing my system back an hour. (put my back up directory under the systems root) Luckily it looks like I was able to get the partition saved to an img file after the fact with ddrescue. It’s 3.7 tb, and when I try to mount it nothing loads up under the folder. I checked the contents by dding and greping everything to the terminal it looks, like everything is there.

The only problem is I’m not sure how to get the file open for rsyncing everything back. I only have 3.4 tb to write this 3.7 tb drive out to on the new external hard drive, and I definitely don’t want to overwrite the old drives partition with it till I verify that the rollback has everything. I think it’s only 2tb that actually has any data on it. Any ideas on how I can get this img opened safely?

how are you mounting the img?

I’m using:
mount -o loop,ro partition.img mountpoint

I’ve also just tried mounting:
mount partition.img mountpoint

It gets recognized as an ext4 partition when I mount it. There’s just nothing showing up.

Currently I’m cping the img file to a sparse file, and going to see if I’ll have room to dd that out on the end of the disk.