The threaded outlet from the tank seems to be the same size as the nut on the end of a flared fuel line end, the same as would fit into the outlet side of the petcock. An adapter that would allow the use of the nipple would be pretty flimsy. I am sure it exists somewhere but I wouldn't know how to start looking from where I am. After the latest installation all of those potential leak points are tight, except possibly for where the line goes into the fuel pump. The connections around the petcock have never been a problem, the leak has been from the threaded hole on the bottom of the tank.
The fact is that the threaded hole on the old original tank is not at all the same as on the replacement "original" tank. I cannot be the only bolter who has bought such a tank - in this case from LMC who I consider a quality supplier but the same tank is probably sold by others - and I am surprised that it seems that no other bolter has chimed in after dealing with this situation. The copper line is its own subject but that copper line is not causing my current problems. I would much rather have used a steel line, with or without preformed flares, but I would have to order such a line from the states and that process even for relatively cheap parts is extremely cumbersome and expensive.
So instead I am trying to deal with my problems as farmers have done throughout many centuries, using the available materials to do the best job I can.
I have appreciated all the comments, thank guys! All the mistakes I am making are transforming me into a wiser wrencher. We are all beating a dead horse at this point, the line is not leaking.
