EFI return line

Looking for ideas for the return line for my sniper efi system. Was going to put a bulkhead fitting in the sender unit but seems like there is not enough room for one to fit. Thinking of drilling the tank next to the sending unit and putting a bulkhead there or buying a sender with a return but the return line is only 1/4 inch and it needs a 3/8 line. Maybe drill out the 1/4 line and solder in a 3/8 line? Thanks for the ideas.
doesn't the top of the tank have more than 1 vent tube you can use one of them also