Trying to re-install Windows 7, "Need 64bit" error

So I recently had to format my hard drive, removing my previously installed Windows 7 partition. I'm trying to re-install Windows 7 now, only to get an error stating that I need a 64-bit Windows installation. The installation disc I'm using has both 32-bit and 64-bit, so I'm not sure why it's not letting me install it. This is the same exact disc I had used to install Windows on this same machine a while back, which makes this issue even more frustrating.

Looking at previous topics about this subject led me to do an edit to info.plist in the Bootcamp application (by adding my model identifier) but it renders the bootcamp application useless as it crashes immediately upon startup.

Any help getting around this stupid barrier to install Windows 7 would be greatly appreciated.

I'm using a 2012, 27-inch iMac running Yosemite.