Did the old Centre St. Branch connect to the NEC under the CNJ bridge in Newark? There is clearly a ramp to the NEC there, and I recall an old branch line running along Rt 21 in the late 80s.
I think the ramp near the CNJ was part of the shoo-fly when the "new" Penn Station was constructed in the 1930s.
The Triumph book has an extensive section on the building of railroads in downtown Newark. I'll see what it says about the Center Street branch. it would seem logical that the branch would connect with the line up from Elizabeth in that area.