Thanks for the reminder about upgrading the fuel line to USCG certified alcohol resistant fuel. Wise advice.
Like you, my goal is to keep the original look while incorporating subtle modern upgrades that help make the boat more pleasant to use and maintain.
On the electrical front I have several projects planned. As you mentioned, I'm upgrading my fuse panel from the original, exposed, round fuses, to a more protected, blade fuse panel from Blue Sea Systems, along with their 'add a battery kit', which includes Dual Circuit Plus Battery Switch and an Automatic Charging Relay. I'm adding a house battery to separate starting and accessory duties. This is because I'm adding a Simrad Go9XSE GPS/Chartplotter clubbed with Simrad Sonic Hub2 and small JL Audio 2 channel amplifier for entertainment. This setup allows blue tooth devices (mobile phones etc) to connect to the Go9 XSE to play music or video. Additionally, the Sonic Hub2 has an AM/FM tuner built into it that is controlled by the Go9XSE. I'm adding a fuel flow sensor which is connected to the Go9 XS and will help gauge fuel economy. A later project is to add a 12 Volt refrigerator compressor. The boat has a classic 1970s camper icebox incorporated into it, (under the Pilot's Seat) and retrotfitting a cold plate to it, looks fairly straight forward. Lighting, Windscreen Wiper, Bilge, Blower, Horn, Spot Light will all be put on house battery circuit.
What is your view of wire ground blocks? Meaning are you running both feed and ground wires to each accessory, or do you run feed wires to the accessories and ground wires to common ground blocks. On my boat, there are common ground blocks which simplify grounding the lighting, fuel system components, blower, and bilge pump in the stern. The outdrive is Mercruiser, so there are fairly nicely designed and robustly built wire harnesses for the engine (including gauge wiring) and the controls. (ignition, throttle, transmission and trim)
I still don't understand modern battery technology. I find the capacity, format (wet, AGM, Litium), house vs start, and price range choices daunting.