line lock on 73 duster ?

we've been working on a 73 duster my son got for about three year's now. it sat for year's before he got it. over these past year's we came to the conclusion it was built for street & track reverse valve trans drive shaft cage 488 gear now 323 ect. ect. there was a switch on the shifter which we took off that I see was a line lock which is what Dart 4 forte has for sale my ? is what should I look for to reinstall if I was back in 1973 it would be great to reinstall any help would be great on hooking it up again wiring ect.thank's