I looked at trying to make a 7.5.5 image. It looks like the only way to make it fit in 7.5MB is to install the minimal system "for this macintosh", which would be an SE/30. So, using MESS, I attempted to install 7.5.3 into an image for an SE/30. Install worked, but switching ROMs from SE/30 to IIsi, 1) the image was no longer bootable in MESS (it said machine wasn't supported), and 2) The SE/30's SCSI doesn't work in MESS when using the IIsi ROM.
So I got out my SE/30 to try to get an install working, and it looks like my SE/30's analog board needs some help since my video is all messed up.
Sorry about that, but it's a long way of saying I don't have a 7.5.5 image for you at the moment...
I have OT 1.1.2 installed under 7.5.5 with an Asante MacCon IIsi/SE/30 PDS card. Should I also install this "improved" driver along with what was placed in the extensions folder when I installed OT? Do I need to remove another driver to prevent a conflict? http://www.mactcp.org.nz/ethernet.html