67 sending unit bushing

[Tower's Trucks]

I have a 67 with a 283 2 barrel. I just bought the wrong sending unit. it has the larger pipe (3/8 inch) and bigger fitting. Instead of sending it back, I want to buy a bushing to connect my small fuel line (5/16) to the larger pipe on this sending unit.
Due you know what size bushing I need to ask for at Home Depot that will allow me to fasten the small fitting on my line to the large fitting on the sending unit? Also, is it a special type thread (pipe thread or whatever)?

Thanks!!