Does this patched version of scsi.amhd work any better? I removed the A3000 SCSI check from it. (Remove ! from URL after pasting into your browser's URL bar.)
Code:
https://www.media!fire.com/?6x9oddzj5a3tbi1
Extract the archive and copy/rename the file to DEVS:scsi.amhd
I just tested it to boot Mac System 7.1 from hard drive on an A2000/A2091/Kickstart 3.1 config.