If I understand what you are asking. In order for you to restore a boot disk you would have had to create a DISK Image while it was still a bootable disk.
Yes Macrium Reflect will clone/copy all partitions on any UEFI GPT Disk and restore your your disk or a different disk as in SSD to the original factory condition. But it would have had to be THE boot OS disk when you made the Image.
As to whether it will work since you created the image under Win 7 I don't know for sure either way, Reflect tech support is very good and the may be able to answer that question.
All that said, if you did create the win 8 DISK Image before you installed win 7. It should indeed restore your Disk to the condition it was in at the time you created the Image. The Key is if you created a "Disk image"
If you only made partition images or Back up's, its not going to work
I just clean installed Win 8.1. i'm making it look and work just like Win 7, it takes a few tweaks but I'm happy so far. I have been running Win 7 HP for over a year now since bought this G74VW.
Clean Installing UEFI GPT, I think created 5 partitions one of witch is a recovery partition, no not an Asus one a win 8 one. You really don't need the factory anyway. Reflect will create reliable Images that will restore with out issues on UEFI GPT Disk I don't know of any other Imaging software that will for sure. Several say that they will, but for some reason they can't create the boot partition correctly.
I hope this has been helpful
G752VY-DH72 Win 10 Pro
512 GB M.2 Samsung 960 Pro
1 TB Samsung 850 pro 2.5 format
980m GTX 4 GB
32GB DDR 4 Standard RAM
Z97 PRO WiFi I7 4790K
Windows 10 Pro
Z97 -A
Windows 10 Pro