mechanical fuel pump question

I posted under "General" questions and did not get any response so I hope it is ok to post here also.
What I have is a problem fitting my new 3/8 hard line from tank to stock fuel pump 5/16 nipple on 273 motor. I know I should have looked closer BUT here I am. Do they have a stock pump I can swap out with my old one that has 3/8 lines? I really don't want to "clamp down" on a 3/8 rubber hose to get it to seal on the smaller pump unless I have no other choice. Any help is welcome. :D