Good write up. Using the same 69 tank on my 66. I was going to get a NOS GM gas gauge from a 70-80's from ebay and pilfer the 90 ohm resistor off the back of the gauge and added it to the 66 gas gauge.
Dophin also makes a ohm converter
https://www.ebay.com/itm/26550897351...cAAOSwVbph7t4D