Fuel Tank / line question Options

[tod914]

Been browsing a bunch of previous posts, couldn't find what I was looking for.
Car is a 74 2.0. The fuel pump was relocated to the front. I'm in the process of
replaceing all the line under the gas tank and on the pump. Don't like the stuff that they used. All the other lines I replaced under and in the engine bay including the step hose, and the 7x13 german hp braided line.
So, I have the 7x13 high pressure line, but what is the other size line that is required ? All I seen in posts are 3/8 ths. What is the metric size I would need.
I havent pulled the tank, trying to do it from under the car. Is the feed and return lines/nozzles on the tank itself the same or 2 different sizes?
Also taking Cpts suggestion with the metal bmw filters. Other question, The step
hose that is now in place in the rear fender well is going to a filter, and then to the engine bay line. ( car has 2 filters in it now, 1 before the pump, and the later). With metal filters, is that acceptable? I'm under the impression it's not a good idea to use the plastic one back there.

Thanks again

Tod