Fuel hose AN6 or AN8

You have the -6 so there is the return line. -8 for the feed. Since you may second guess yourself on it get it over with. It won't hurt anything (except the checkbook.)

Wish I had run a return line on my last hotrod. Some of the problems I had with fuel would have been corrected....

JW

The opposite is true. If anything you want the return to be "as large as or larger" than the supply. This is because the return is low pressure. You do not want to cause any back pressure in the return