UUCP was only a couple years before TCP, and isn't really an equivalent (it's fancy file transfer with a little remote command exec sprinkled on in the end) and natively its dialup oriented; it usually requires some other L3 protocol to run over networks.
There was a time when IPX/SPX was a contender. Xerox pitched XNS directly at TCP. DECNet/OSI was around. There were a lot of others...lot's of experimenting going on at the time.
If you're interested in a more "modern" UUCP, there's NNCP [1] (HTTPS ver here [2].) It continues to mostly be a file-transfer protocol with a bit of signaling added on.
There was a time when IPX/SPX was a contender. Xerox pitched XNS directly at TCP. DECNet/OSI was around. There were a lot of others...lot's of experimenting going on at the time.