Are the Harmonic Balances interchangeable?

I just swapped my 1973 Dodge Dart Sport's Original 318 with a 1968 Dodge Charger's 318. My dart originally had A/C and the charger did not i realized the crankshaft pulleys were different and nothing would line up because i had swapped my 73 Water Pump and Power Steering onto the 68. My Dart and the original engine are in two different buildings and i am curious if the harmonic balances are the same or if the 73 Balance needs to be installed on the 68 to make everything match up better