gas tank fuel line question

[69Tom]

OK, so I've been trying to sort out this 70 C/10 I picked up. After removing the seat, I noticed this gem of a set up. No grommet on the floor. After receiving the grommet I ordered, I notice why.

The duct tape is on the connection is obviously not factory. That should be a hard line going to the sending unit, correct? And the correct sending unit should receive a 5/16" line for a I-6 250, correct?

If I were a betting man, I'm thinking the wrong sending unit was put in the tank and that's a 3/8" line there. Can any of you tell by the photos?

If it is the incorrect 3/8" sending unit, is it advised that I swap in a correct for a 250 5/16" unit and hard line, or doesn't it matter much? (I'm definitely getting hard line to the sending unit--just depends on what size).

Thanks for the advice.