Derek;
this is what I have tried so far.
mac os 7.6.1 (lc 475) AppleTalk/localtalk(w macTCP and appleshare 3.8.3)
to os 8.1 (lc 475) ethernet(ethertalk?) to PC box running netatalk and afp
3.1.
the os 8.1 box is running IpNetRouter.
connecting from os 7.6.1 to PC with appleshare and ethernet
It appears that nobody has mentioned Netpresenz and Anarchie (now Interarchy)
from Stairways Software.
Netpresenz is an HTTP and FTP server that runs on OS 7 and perhaps earlier.
Interarchy is the client but it has much more.
With Netpresenz running on vanilla OS 7.5 it's possible to use