You could post the EPROM files you have online somewhere for other
people to take a quick look. Maybe create a thread on the vcfed forum
and add them as an attachment to a message there. If you zip them up
they should be small enough for an attachment.
I have only tried using IDA Pro a couple of times. I haven't learned
how to use it well enough to be what I have used for similar 8-bit CPU
disassembly tasks in the past. I have just written my own basic
functionality 8085 / Z80 / 8051 disassemblers when I have had the
need. Not too hard to make it smart enough to be able to specify known
entry points (for example reset and interrupt vectors) and have it do
reachable code traversal from there. Some things require manual
intervention and iterative refinement, for example any indirect jumps
through call tables, or calculated jumps. Using a professional tool
might be quicker, but you might learn a lot more along the way doing
things yourself.