How would you run the return ??

I would silver braze it right into the tank. Start with a small sharp sheet metal awl to form the start of a hole, and enlarge it with a larger one, until the fitting/ tube you are using will barely fit, then braze it in place. Do NOT go small. I went to small because at the time I was just wanting a vapor return system, and later went EFI. I'd put in some sort of fitting you can adapt up or down, or else 3/8 tube. Steel or copper