Got to: http://adtpro.sourceforge.net/ and download the latest copy of ADTPro. With this program, and the right serial cables, you can connect your GS to your Mac and transfer the disk images to the GS which will write them to a 5.25 disk or 3.5 disk as part of the transfer program.
With ADTPro you can eliminate the hastle you seem to currently have trying to get your Apple II programs from the Mac backto the GS.
Just a thought,
Dean