Ralley Gauges Pegged,What Gives?

You didn't mention the oil pressure gauge. What did it do ?
The problem is most likely a faulty limiter which is inside the fuel gauge.
There isn't an easy way to temporarily disable the darn thing.
If you're willing to drive without working gauges you can disconnect all 3 senders.
You'll need to insolate those connectors. The one on the oil pressure gauge rarely retains its insolator.