I'd reinstall - if sda7 is your root partition then use that to install grub also. As long as you have a live CD you can put grub back in the MBR pointing to the config files you want (on your boot partition).
You can copy stuff over to your boot partition later if you want ... but at least that way you will have the correct boot parameters for gOS and there's no danger of overwriting the existing boot partition data.