Ozmodiar-X

I need to increase the fuel line size on my SA tank on the feed from 5/16" to 3/8" and the return from 1/4" to 5/16". I took it to a rad shop today and they said the only way they could do it is if they knew how the lines inside went. Does anyone have a picture of the inside, or know how they go? Do they got straight down like the 81-83 do (or at least think do)? Also are these lines welded in or solder in?