NOS senders for the 80's models are $200+ on Ebay when you can find them.

I have in the past used a Wema tank sender & had my IT friend solder a diode or resister or something in the line to make it or you can do what I do now when I use them which is taking a fuel gauge apart & refitting it into the stock cluster

Wema makes them whatever length you need & you won't need another one ever again