that guide is just showing you how to copy the kickstart rom from any physical amiga to use in an emulator. the concept is similar (though easier) if you simply own an kickstart chip. or broken amiga or just a motherboard.
I would recommend Amiga Forever by cloanto software. Even if you have a real amiga, Amiga Forever has all the roms from 1.0 to 3.1, as well as os discs, games, apps and demos.