Troubled by gas

I'm still troubled by the lack of odometer and fuel gauge and I need one or preferably both working. I swapped out the new instrument voltage regulator for some homebrew solid state electronics but all that did was stop the gauge from reading full. I took the odometer/speedo apart and found that mechanically it appears sound and works on the bench, however when reinstalled in the car the odometer still doesn't move. I've replaced the speedo cable in case that's the problem but I've yet to test it.

For the fuel gauge, I've taken the tank out and ordered a new sender unit. The original below was pretty crusty looking and the resistance across the range was all over the place and inconsistent. I'm hoping that this is what's causing my gauge to read less than empty.

The tank has seen better days and there are 3 small holes in it that i'll be plugging up. The interior of the tank has seen better days too and although it doesn't look rusty it's full of crud. Also looks like a previous owner hit something hard, as the bottom is all beat up and has been repaired with a big patch of solder. A new tank is about $200 but I'm going to see if I can get this one clean and serviceable first. 

On a positive note I managed to get the front bench seats out and using the trusted P B Blaster the tracks are now free and the seat will slide easily.