I saw that Publication some years ago and have always been intrigued by the 'University' station and its serpentine connection. As far as I know, no specific plans were made for this, unless they did and said "Ugh!" and threw them away.
I had a peep on Google Maps to see how they would have achieved this so I put the University station at Grove Street on the Victoria Tunnel.
Two routes emerged with a bit of retro-crayonning.
The straight Pale Blue line is the Victoria Tunnel, Amber is the probable position of the University station. Line A: Pale Green (lower) is the line that joins up with the headings south of Central. Line B: Pale Turquoise (upper) is a more direct route to Central. Line A radius 250m. Line B radius 320m.
Line B radius 360m
Line A radius 250/260m. Dark and Light blue lines are the Northern Line. The apex of the curve at Pilgrim Street at the Institute for Performing Arts touches the Wapping Tunnel.
Central Station and environs. Note I've indicated possible station expansion. Line B starts at Newington.

Ignore the pins, that's just something else.
Now I've seen this, all I can say is - well - thank God they dropped it. It's truly horrible.
The excavation at Grove Street for the station would have been colossal and hugely expensive. Victoria Tunnel has a gradient of 1/57 and you would have probably been fiddling about with a 1/30 gradient to get the line under the Lime Street approach, and what the RC Cathedral authority would have said, I don't know, even though the tunnel would have been very deep. Built in the 70s, you may have just got away with a station on a gradient followed by a steeper incline, but nowadays I'm sure the ORR would be looking very hard at all this and asking difficult questions. At least Line B skirts the Cathedral precinct and the curves are easier, but it would almost certainly meant excavation at Central for extra platforms but the Grove Street problem remains.
I think those in authority may have been given good advice on this scheme and ditched it at the first available opportunity.
Google My Maps.