I recently bought a 60 Impala that the motor had been swapped out to a 350 with Weland intake.

I am wondering, what sending unit should I be using?
my OEM gauge says i'm almost HOT (Intake).
The junky aftermarket one says I'm around 200 (in head).

Can anyone suggest what sending unit I should be using. The OEM will not fit, larger pipe thread than what is in the Intake.