Spent the day making slow but useful progress on the wiring. Spoke to Ed Smith re controlling ignition interference on the radios - and his advice was to keep the mag ground wel away form the common ground - run a separet cable right back to the engine close to one of the mags. So I pulled through another cable and grounded the switch next to a mag.
More cable sorting and wiring planning. Bought some heavier connector plugs to connect the power to the panel. All panel connections will be "pull" disconnect so I can remove the panel whenever needed.
Grounding the mag return to the engine near a mag.
Collecting the wires for ignition switch assembly.