Going to switch out the sending unit..

Those 3/8" pickups have a 1/4" vapor return.

are you thinking that is not enough for a fuel return line?
im just running a mechanical fuel pump, so i figured right now, there is zero fuel returning
even a hampered return would be better then none, right?

(i would have to check, the sending unit has been sitting in the garage for over a year now, but i do believe the return is smaller)

What's your plans for your (I assume OEM) sending unit?

If the sender is working good and it's OEM, I would remove it and have the 3/8 line added to it. The sender curve on aftermarket senders is horrible

the sending unit that is in there now is an aftermarket unit, and the curve is not what it should be