Hi,
I have an original of Space Quest III and it comes on four disks, not three...
The manual states that Workbench should be booted prior to loading the game, but I found that the first disk automatically boots and loads the game anyway. I had no disk swapping hassles (tested on an Amiga 500, 1Mb RAM, KS1.2, single internal floppy drive).
Don't forget to look out for Monolith Burger!
- Ali