Brent and anyone else interested in the Summit sender
I tested it in the car (56 Fairlane) out of the tank, I disconnected the factory sender from the harness and connected the sender to be tested via jumper wires. The results are hopeful as this being a good replacement while keeping the stock King Sealy gauge


Photos of the Gauge and Sender at bottom stop, note gauge reads 1/8 tank while sender is at bottom stop. if you remove the wire the gauge will go past E so it needs more resistance than the sender provides.


Photos of the Gauge and Sender at 1 inch from bottom


Photos of the Gauge and Sender at 2 inches from bottom stop


Photos of the Gauge and Sender at 3 inches from bottom stop


Photos of the Gauge and Sender 4 inches from bottom stop


Photos of the Gauge and Sender at 5 inches from bottom stop


Photos of the Gauge and Sender at 6 inches, the top stop. I do not think the float can go that high in the tank as it would be above the top flange of the sender
In conclusion,I think this sender could be made to work with a small resistor in series to make the empty resistance more like 280 - to 290 ohms. the car harness and ground thru the chassis may add enough resistance to correct this, I was using short test leads to the back of the gauge.
Only other thing I want to test is what happens at higher battery voltage, I was testing with engine off and 12.10 volts. 13.8 running may raise the readings slightly as 56 has no instrument voltage regulator. Will see if I can run the same test with a battery charger on to raise the battery voltage tomorrow