Firstly: Get a second 3.5" drive. It will make your life SO much easier, and plenty of forum members will sell you one.

Then, get the disk images for GS/OS from Apple's site:

http://www.info.apple.com/support/oldersoftwarelist.html

Convert on an older Mac and use one floppy drive to install to the other (if you don't want to get another drive, I can make a Mac Disk Copy image of my IIgs boot disk(with half-working ImageWriter II drivers) and e-mail it to you)

Afterwards, I'd suggest getting Asimov and loading it onto a floppy along with disk images of whatever Apple II software you want (Asimov writes Apple II disk images to 5.25 disks)

http://www.ninjaforce.com/html/products.html

http://www.virtualapple.org/ (Games! Yay!)