Looks like my Fuel Sender may be bad and there are no direct replacements. Has anybody dealt with this on the early 60s B-Bodies? It looks like there are people who will rebuild but the cost is astronomical and the time frame is measured in months. Is there a universal that works or am I stuck using the odometer?

1964-older GMs use a 0-30 ohm sender. 1965-newer use 0-90 ohm. Unfortunately, you're stuck either finding an NOS replacement, a good used one, or repairing the one you have. Most generic senders for aftermarket gauges are 240-33 ohms, so they work backwards with stock gauges. And any adaptation like that will likely cost more in the long run than having yours fixed. There is no cheap way out of this.