...

It seems that sdc4 is bootable

The sizes seem bizarre

Partition types are rather meaningless.  They are there and everyone
seems to set it, but when wrong it does not seem to matter.  At best
it is information that is sometimes right.

I have not seen that the partition type has to have any relationship
to what is actually on the partition.

Ontrack was typically used to get around some windows size limit.

What size is the disk?

And odds are these are some variant of a windows fs.

So do "mount /dev/sdc1 /somepointpoint" and see if it mounts and/or
see what the error is in dmesg/messages when you try to mount it.

Could it be an extra empty space some partitioning tools leave behind? Make sure the partition is as big as it can get.

B