Voltage Limiter Replacement

I'm replacing the wiring behind the dash of my 65 Dart, and want to upgrade the gauge limiter while it's all apart. I have the external limiter and got directions to open the fuel gauge and disable the internal limiter but my gauge looks riveted closed and trying to get in there seems like a disaster waiting to happen. I came upon a post here from Redfish with instructions on how to do it without opening the gauge. It looks easy enough but it says to reroute the blue with white stripe wire to the original limiter and that's where I hit a snag. My shop manual shows the blue/white wire going to the oil light at ignition, and a black wire to the fuel gauge. Can anyone who has done this please confirm to me which wire should be rerouted? I'd hate to make a mistake and ruin something.
Thanks.