If the question is where do the cables run from the rear to the front on a C-25, the answer is:
They go through the port (that's left, isn't it?) lazerete, above the cutout in the side panel, through a hole in the aft cabin bulkhead, outboard of the head bulkhead and into the under sink area, thence forward to the throttle console and up to the electrical panel. It's easy to trace. Just follow the steering hoses from the steering pump (wheel) back, or the hoses from the engine forward.
Use a fish tape to run the cable, one segment at a time. Tape the front of the cable to make sure it goes through smoothly, especially if it has a plug on it. I had to remove the refrigerator to go through that compartment, and drill another hole for the wires/hoses/cables I was running.
I'd support the flowmeter with a strap or tiewrap to some structure so that the hose doesn't hang directly from the filter.
Boris