It seems you have a 32-3 like me. There are so many variables, it is impossible to say how much the labor would be. In my case, I ran a new depth coax from the V-berth area back to the bulkhead and it took nearly half a day - a real pain. Ericson did install tubes to run the wiring through, and some have had success with a vacuum sucking through string to pull through the wiring. I have since started to run my wires through the bilge which is not great but okay as long as there are no connections to corrode. Then you have the problem of replacement senders and heads requiring a different sized hole, so that would entail fiberglass work.
The only instrument I really care about is the depth sounder. There is a wireless handheld depth meter on the market and it can be mated with Airmar's in-hull 200mhz transducer. So for about $275, you could get away without having to run any wires (other than power to the sending unit) or drilling any holes.