The KS 3.x ROM is 1MB in size, so if you have extra ram you can "soft kick" your A600 to run KS3.0 or KS3.1. All you need is a utility such as relokick and the KS 3.x ROM image. Only trouble is, you would have to load this disk every time you want to use Workbench 3 stuff. Easier option is do as Marco said and buy the A600 3.1 ROM.
