Alexander51,
From what I read in your post, you are basically wiring a '77 that just happens to have a '54 cab on it. I think your best bet would be a schematic for the '77 truck. Wire colors will only be relevant if you have a schematic.
You will have to transition from the new system to the old at some point. This doesn't mean old wires, but dash gauges, headlight switch, sending units etc.
Be sure you use adequate wire gauge to match the device. Utilize the new fuse block to protect all your circuits. Get a wiring diagram and good luck.
Stuart
