I installed an EFI tank in my Challenger 5-6 years ago, the first sender was a float type and was as shitty as the typical repos... But then I heard about the floatless style senders... Bought one & it was nearly spot on out of the box....
I recently got another old car back & early on discovered it needed a tank.... I bought another of the Tanks Inc tanks but set this one up for a carb... And used a float less style sender... And it is also nearly perfect OOTB....
Can't use this style sender with the original tank but if your changing the tank & have the option of a five bolt sender.... Consider trying a float less sender...
Floatless Fuel Sending Unit
1966-67 Dodge Charger, Coronet, Belvedere, GTX EFI Gas Tank