I sort of have the same zoomed in problem but in different situation.
My main monitor is 2560x1440 and my secondary display is a HDTV which is 1920x1080.
So I start 7th Heaven and FF7 in windowed mode from the main display and when I move the game window to my HDTV the game get zoomed in and when I move it back to the main display it remained zoomed in.
I've tried all the suggestions here for the DPI on ff7.exe, ff7_bc.exe, 7th heaven.exe to no avail. Also changing Windows 10 scaling option for secondary display to 100%.
I also checked settings in FF7Config.exe, I CAN set where the audio goes to for example either to my main speaker or to the TV but there's no option to set which display to use, there's only one Primary display and no secondary display to choose from, I wonder if I need to do something for it to see my HDTV?
The only way to get around this for me is to set my HDTV as the main display :> So when I start 7th Heaven and FF7 it will just show on HDTV with the correct scale.
Any other ideas on how to play it on a secondary 60" display
?
p/s: My HDTV is connected to my Home theater system and then connected to my PC GPU.