Complete electrical failure and absolutely no gyros: If you truly can't stay in visual conditions, there's really only one last resort. With a "known" 400 foot ceiling, get over flat terrain, or in this case, maybe even over the ocean, setup and trim for a good stabilized descent, hands off the yoke, rudders only for any corrections, let down thru the clouds while watching altimeter, hope you stay stable thru the goop until underneath in visual, then scud-run. Turbulent air would of course lower the percentage of successful outcome, and probably more likely with a 421 vs. lighter airframe like a 172. Absent any outside assistance such as a "formation shepherd" from the Coast Guard, or such, that's about all you can do.