We are ready to take the plunge and install dedicated lines. I'm on the 14th floor of a 1960s Manhattan condo (174 units), so there must be all sorts of bad karma coming through the current lines. I'm hoping running dedicated from the breaker boxes will bring at least some improvement.
Sorry can't help you with an electrician in NYC.
You might ask the building manager who he uses for the main house power of the building.
From what I have read about NYC all branch circuit wiring has to be installed in a metallic raceway.
Beings your building was built in the 1960s that could be a good thing. Too late for BX wiring and Too early for AC or MC cable wiring. What that means the branch circuit feeds from your electrical panel will be single insulated conductors pulled in either EMT or rigid conduit. Depends on local code back then in NYC.
If there is room in the conduit near where you want to add the dedicated circuit the electrician may be able to pull the new circuit in the existing conduit. Otherwise the new circuit would need to be installed in 500 or 700
Wiremold or some other type of metal surface raceway. (Wiremold also comes in a white finish.)
If the electrician can use an existing conduit and you want 2 new circuits you do not want a multi wire branch circuit. (2 hot conductors that share a common neutral conductor.)