The KS1.3 & KS3.1 SuperKickstart files have somehow found their way into his inbox from some anonymous source

Remember that as soon as you fit a CPU upgrade you can no-longer use a KS1.4 ROM.
Probably worth making your own A3000 KS3.9 EPROM using Doobrey's ROMsplit & Remus tools. I think they support the A3000 KS3.1 ROM files.