Fuel Guage Goes Up Then Partly Fades -- 72 Swinger

After fixing some more pressing stuff, I'm back on the fuel gauge issue. I'd like to start with the "resistor test" by seeing what readings I get at the gauge with appropriate resistors placed between the sender wire and ground. So now to figure out how to do this: can someone tell me if I'm on the right track?

Since I don't have resistors on hand, my plan is to buy a pack of 10 ohm resistors. I'll put 7 of them in sequence to get 70 ohms (simulating ~empty), 2 in sequence to get 20 ohms (simulating a tad less than half) and one in line to get 10 ohms (simulating ~full). Then I'll put each of those three configurations between the sender wire (one at a time of course) and see where the needle lands.

Before I order those resistors, does anyone know if the tolerances of the resistors matter? (looks like they have the 10 ohm resistors at 1/2 Watt, 1 Watt or 5 Watt).

I may be way overthinking this, but if I remember Ohm's Law correctly, V=IR and P=IV, so P=V^2/R. For the 10 ohm reisistor, that would mean that there is about 0.5 amps of current running through the sender wire and P would be about 2.5 Watts. For a 20 ohm resistor, 1.25 Watts, and for a 70 ohm resistor, 0.36 Watts.

So if I just get 5 Watt resistors, am I good?

Sorry, this is getting a bit nerdy -- and possibly doesn't even matter.