i have a few bikes with copper lines, never had a problem.
the easiest way to do it is to buy refrigeration line from Ace or home depot, and some real fuel line from an auto parts store that will slip over it. i think it's 1/2".
shape the copper the way you want it, you can put an old timey loop in it as long as it's still got a good gravity flow. you can bend the tubing around a small pipe, like a seatpost or something, just do it smoothly so it doesn't kink.
take the fuel line and cut two, inch and a half sections, put one on the carb, one on the tank, then cut the tubing to fit, slip it into the fuel line, and you're done.
make sure you cut the copper tubing clean, de-burr the ends, and blow it out to make sure no copper shavings get into your carb.
i don't even use hoseclamps.
check my bikes for some examples.