Hi Nirav, you are the first person to be interested in my project. Do you want to create an ISO file with the windows 7 shell integrated or just replace your VM's Windows 8 shell with the Windows 7 one? Anyway, they are basically the same thing, you will have to download the windows 7 ISO file from https://www.microsoft.com/en-us/software-download/windows7 or using the Windows ISO Downloader (Edition doesn't matter but architecture and language does) . After its done, find install.wim , go to your Windows 8 edition, find .\Windows\explorer.exe, .\Windows\en-us\shell32.dll.mui, .\Windows\en-us\explorer.exe.mui and copy them into a spare folder. The next step is to download Windows Explorer Wrapper file (wrp.dll) from here: https://tinyurl.com/ycc7okgw and place it with explorer.exe, now you have all files collected and you can replace the Windows 8 ones with those files and restart Windows Explorer. If you wanted to integrate it into an ISO, it would be extremely hard as its nearly impossible to find or download Windows 8 Disk Images from Microsoft, so go to torrents, warez websites and other places to find a copy then VERIFY the checksum to make sure it hasn't been modified. Then mount install.wim, replace files and unmount the wim file. Test your ISO file to be sure that is working.
This is very brief and if you don't under anything, comment below.
P.S: IT IS ILLEGAL TO DISTRIBUTE THE MODIFIED DISK IMAGE SO YOU CAN ONLY USE IT YOURSELF.
Thanks,
SnowBall