I did a TPI in a '62. The speedo conversion from electronic to cable can be handled with an adapter, call Street and Performance. Try to keep all of the electrical stuff that is not engine related except for oil pressure and temperature gauge and alternator on the original wiring and switches. You will need a relay to run the TBI since you will quickly toast the original ignition switch. Simply use the coil wire from the igition switch to the swithced relay. Other than connecting a hot wire to the starter hot connection for the ECM in order to retain the ECM memory when you shut off the engine, all of the other harness connections ought to be good to go. You will need a high pressure fuel pump inside the tank and a return line from the fuel injection unit. This is not rocket science and all very do able.