This is what I've been fighting with for the past few days.
Fuel pass through 1 by
Kevin Frank, on Flickr
I had to weld a few different angles together to make a pass through in my fuel tank enclosure for the stock fuel filler. The vent pass through only required a straight piece, so that one was easy. The fuel filler involved a bunch of different angles, so it was a bit more of a pain to do. I'll get paint on the enclosure (some of it will be impossible to get paint on once it is in) and get it welded in position, pictures of that will be forthcoming.