Follow the ABYC wire sizing chart and see if the conductors are suitable. Probably some loads would need larger wire. Remember the circuit lenth is round trip, from source of power to ground return.
I like just upgrading to EMI tested LED nav lights. Usually can match style , there are so many styles available. But you always can find a socket from NAPA and there is no end to led replacement bulbs.
I always believe that maintaining on board batteries correctly is the answer. Why would you expect to drain your batteries? Is there a problem that needs addressed?
Jump pack is just extra stuff on board in my opinion.
Compare the running readings to a good quality automotive service tach, if they are pretty close, all is good. If the boat tach doesn't match, replace it.
OEM wiring diagrams usually don't exist in the boat world. Probably have to start tracing. Power probe is my tool of choice for this job. Can pick up a power probe at Harbor Freight now.Power Probe
There are many sources for the Delco Voyager marine ignition kit. Mad Props on u tube has a video on it that is pretty good. He is also a member here. I switched to it in place of TB when I repowered. 350 Chevy.
