There's no reason to tie the rear to the front. Use the wires for the rear on the rear. Don't connect the brake light wire to the switch.
The '54 should have holes in the dash panels for indicator lights. You can get salvage yard sockets to install the bulbs and tie them to either the front or rear circuits.
If you don't use in-dash indicators you will need to connect the pilot light wire from the switch to the "P" terminal of a 3 prong flasher. This will light the pilot light in the switch housing. If you do use in-dash indicators you won't need the pilot wire and can use a 2 prong flasher.
My
tech tip might be helpful.
