Yes use Ultraiso and delete the install.wim first. Then in the bottom left pane locate W7 on your computer and the new install.win. You will see the install.wim in the bottom right pain. Highlight it and using the task bar for the bottom right pain click on "Add" Then go to the very top task bar and click on the save icon. It will then rebuild the ISO with your new install.wim.
I used to build W7USP2 ISOs in the past and distribute them for free. Now I build such customized ISOs for a few people, when I have enough free time. If you want to create a good ISO then you have to sysprep and capture. I had found a "WPA reset trick" back in 2012 which resets the Windows Rearm counter to 5. I had prepared a guide in 2013, someone uploaded it on scribd: scribd.com/doc/183362181/Building-Windows-7-Sp2#scribd In the latest W7USP2 ISO I created (for a customer) I have introduced the following improvements: -The Virtualization environment used should be Hyper-V. It will help you create an image without the "Battery" icon appearing on Desktop Computers in Device Manager. - Use Windows anytime upgrade to switch between different editions (use the default product key for the specific edition you're upgrading). Capture a snapshot before and after changing the edition. You will use each snapshot to sysprep -generalize and capture each index. - Windows 10 spyware/nagware disable script: forums.mydigitallife.net/threads/64561-Remove-Telemetry-and-Windows-10-Related-Updates-from-Windows-7/page24?p=1186965&viewfull=1#post1186965 - My rebase tool to minimize winsxs size after installing all updates in the lowest SKU. Don't need to run after running Windows Anytime Upgrade. With this method you will get a totally reliable and fully customizable install.wim, that can be easily deployed to various hardware configurations.
As my review there is NO Windows 7 SP2 at all, the final release is SP1.. So, I rather kept legit not use Fake SP2 edition for that Windows 7..