Bad Fuel "Gauge"? (1965 Barracuda)

I've been trying to troubleshoot an ongoing problem with my fuel gauge system. I think I have narrowed it down to the fuel gauge itself, but I was wondering if anyone else has experienced this particular problem...

Before I describe the situation I just wanted to say that I have already (more or less) ruled out other possible problem areas (I think):

I have a new SENDING UNIT (see below for test results)
I have a new "solid state" VOLTAGE LIMITER (from rt-eng.com - also see below for test results)
GROUND tested good.

Ok, so here's what it's doing:

When the SENDING UNIT is at the "empty" position, the gauge shows exactly empty, and when it's at "full" position the gauge shows exactly full. So far so good, right? BUT, when I have the SENDING UNIT set to approximately the middle, the fuel gauge shows a quarter or less and once it gets to about 1/3rd the way up it pretty much shows empty:

View attachment FuelSenderA.jpg

So, once it shows empty then I could have between 0 to 6 gallons in the tank, which kind of sucks trying to predict how far I can go when the gauge indicates that it's empty (I already had an instance where I ran out of gas because I wasn't sure how much was left in the tank).

As I mentioned earlier, I tested everything else. Here are the results:

A) SENDING UNIT - Using a multimeter I tested the resistance which was at about 80 ohms (empty) to about 9 ohms (full) and as I swept the float arm upwards the readings adjusted accordingly (went from 80 to 70 to 60, etc) as you would expect:

View attachment FuelSenderB.jpg

EDIT: See Post#12 below and the article I attached which describes a similar problem with fuel senders on early Ford vehicles!

B) VOLTAGE LIMITER - I also tested the DC Voltage with the multimeter on this device as well. The readings fluctuated from approximately zero volts to various high readings between 4 to 7 volts for example:

0-4 volts
0-7 volts
0-4 volts
0-6 volts
0-5 volts
0-7 volts... etc

My understanding is that this is normal since the RTE voltage limters are designed to mimic the original contact point Mopar limiters (to approximate a 5 volt power source).

C) I also made sure the SENDING UNIT had a good GROUND as well, so that shouldn't have be an issue either.

Anyway, my next step is to replace the gauge with the hopes that it will solve my problems, but before I undertake that project, I was wondering if anyone else has encountered a similar situation and whether there's something else I might be missing.

Thanks in advance!