Fuel sending unit question

[McGillicuddy]

My fuel sending unit readings are way off. In fact the Ohms read opposite what they shoud which leads me to beleive that someone bent the float wire the wrong way, and the Ohm range is far less than the current 33 to 240 Ohm standard.

I'm leaning toward a WEMA reed style sender to replace the old one.

Tank depth is 7-1/2". The actual float tube lengths are 1" less than the stated length.

So my question is do I opt for the 8" version which would leave a 1/2" of space and theoretically a more acurate reading or do I go shorter and know that I'll have just a bit more cushion when it reads empty? My tank also has tapered front bottom and rear top (72 Seafari) if it matters. Thanks for any feedback.