Mack Boring & Parts Company - The Power Behind The Power
Above carries OEM and a after market. They are pretty expensive. I have seen some on e-bay but still high dollar even for used. I would take your old panel and rebuild with water proof led lights (blue sea from west marine). The panel is basically some indicator lights, a buzzer, and some swtiches. Try to use your old rpm gage. could probably buy all the parts for less than $100. used I seen for $400. You could call Mack boring- maybe they have an old one they would sell you.