I use both Grub1 and Grub2 and can confirm both can chainload each other without any problem.

Grub1 cannot access a Ext4 partition because it hasn't got the driver for it. The support/maintenance of Grub1 was stopped almost at the time I entered Linux and nothing has been added since Ver 0.97. Therefore the only way you can rescue a Grub2 system is to boot up a Linux Live CD that support Ext4 which is not a problem with modern kernel.

If your sdc8 has not been formatted in Ext4 then Grub1 can boot it manually using the following information in your grub.cfg:-
Code:
    set root=(hd0,8)
    linux    /boot/vmlinuz-2.6.31-14-generic root=UUID=cebf7cd9-6974-4084-87d8-6024cad3d61a ro   quiet splash
    initrd    /boot/initrd.img-2.6.31-14-generic
The equivalent in Grub1 commands would be
Code:
root (hd0,7)
kernel /boot/vmlinuz-2.6.31-14-generic root=dev/sdc8 ro
initrd    /boot/initrd.img-2.6.31-14-generic
boot
Please note the difference in calling the partition. You can use the original UUID to identify the partition but /dev/sdc8 will work and is simpler. The bits changed by me have been marked red.

Once you are running Linux Mint, go into a root terminal and issue this command to install Grub2 in sdc8
Code:
grub-install /dev/sdc8
Your Linux Mint should be chainloadable from this point onward. One last word it is possible that you may have to do grub-install more than once (if it fails) as there seems to be a bug in Grub2.