From my personal experience most filecarvers like to make assumptions based on which filesystems they detect. You could create a loop device with 32GB offset just to make sure your scanner/filecarver does not get sidetracked by seemingly valid data you're not interested in (i.e. skip the area you know was overwritten). Note the offset should be 512 Byte or 4K aligned. If you know the exact size of bytes that were overwritten, use that instead.
losetup --find --show --read-only --offset $((32*1000*1000*1000)) /dev/sdx
Then you can use any program of your liking on that loop device. photorec is one, there are others like foremost, scalpel, ... knock yourself out.
If you had partitions / logical volumes that started beyond the 32GB mark you can also try testdisk. If you had a filesystem with redundant metadata you could try to fix that too, but you need to know the original partition offset (e.g. 1 MiB) and some way to locate the metadata backups.
This is best done with overlays https://raid.wiki.kernel.org/index.php/Recovering_a_failed_software_RAID#Making_the_harddisks_read-only_using_an_overlay_file
An overlay allows you to run fsck or some other programs that write on a virtual /dev/mapper/sdxoverlay device, without actually performing those writes on the real disk.
