To get Samba on a Classic OS seems to need 3rd party non-free
software. However, netatalk can be run on Linux/BSD so if you can
get the two Macs to talk you should be able to set something up on the
Linux server to get files through it. Macs can do AppleTalk as
either LocalTalk (serial ports) or EtherTalk (ethernet) and also
AppleTalk IP. You'll need to set the 8.1 machine up for AppleTalk
over ethernet.
The PowerMac is running OS 8.1, hence my confusion.
All of the information I've been able to Google covers
OS 8.5 or higher.
My brother-in-law says he might be able to find the
original OS 8.1 CDs if something needs to be on the
computer that isn't.
I am under the impression that there is no version of
Samba for OS 8.1, or that it was unable to connect to
a SMB/CIFS share.