I think I managed to get talk working on this server. Took a bit of work to get it sorted out and I had to modify the /etc/inetd.conf file by hand.

The magic seemed to be:

	sudo apt install talk inetutils-talk inetutils-talkd

And then changing /etc/inetd.conf to include:

	talk            dgram   udp4    wait  root       /usr/sbin/tcpd    /usr/sbin/talkd
	ntalk           dgram   udp4    wait  root      /usr/sbin/tcpd     /usr/sbin/talkd