The Cab signal if still installed on those cab cars should be compatible. There are however changes to be made in wiring, Pantograph up down to be changed to Electric/diesel mode for example.
All key switches need to be changed on door panels and electric lockers, NJT uses differet keys than MNCR.
The Phasing on HEP is suposedly diferent, I don't believe it, is but you never know.
The trucks need rebuild including addition of Disk brakes to the tread brakes.
All seating needs to be changed, half cars are currently empty.
My suggestion paint window band green, put long distance 2 x 2 seating in them and get ready for Albany service