The other issue is that between SPY and University Heights is two tracks in a tight viaduct. Normally wouldn't be much of a problem but Metro North's schedule's a bit packed.
Possible? Yes. I even wrote about such a move (which should pop on my sequel novel's Patreon this month)... although I have the consist come from south, reverse (by towing with an engine) off the Empire Connector to MN territory north of SPY (assuming no wye there), then take the wye in South Bronx before reversing into Grand Central. Granted, if a wye in SPY were to be put in, it would save a lot of move swapping (the consist would be towed straight in to GCT).
Lots of coordination here.
Possible? Yes. I even wrote about such a move (which should pop on my sequel novel's Patreon this month)... although I have the consist come from south, reverse (by towing with an engine) off the Empire Connector to MN territory north of SPY (assuming no wye there), then take the wye in South Bronx before reversing into Grand Central. Granted, if a wye in SPY were to be put in, it would save a lot of move swapping (the consist would be towed straight in to GCT).
Lots of coordination here.