I don't have the computer but I just downloaded GSPlus app on my MacOS.
I found ROMs and I have a tone of games from eXoAppleIIGS package as .po files.
No idea :) I've got the real hardware, but never used any of the emulators. .po files are prodos ordered files meaning they're disk images, so you'll need to look for some way to mount them. Most likely they'll be 800k images o you'd be mounting them on the 3.5" drive usually slot 5 drive 1. However there is nothing stopping a .po file being a 140k 5.25" images which would normally mount of slot 6 drive 1. You just let the size of the file guide you.
Once you figure out how to mount them, you'll also need to figure out how to make yourself some kind of image to mount up as a hard drive, after that installation of GS/OS ought to be a doddle, just mount the installer image, boot it, and tell it to install on whatever your HD image is. It'll probably take 3-4 disk swaps.
ST
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