I have to make up some new oil lines to replace damaged ones, the lines are made out of 1/4 inch OD soft copper, The fittings I will call a inverted flair for lack of a better name. It seems like the copper line that sticks 1/8 inch through the end is flared, Can I simply re use the old fitting after I ream it back to 1/4 inch and I was thinking about using a center punch to flair or swedge the end of the copper. What is the proper way to make up this joint ?

Looks like you may be able to use a modern compression fitting with the ferrule and the nut being separate pieces? I don't imagine the nut/ferrule combo shown would be reusable as after you ream it back to 1/4" there would be nothing left to compress back around the tubing and seal it up. My thirty has the same type of fittings and one of them didn't have the taper on the nut that yours has so someone had stuffed some small leather rings in there. I was thinking id just go back with modern compression fittings when I start putting mine back together. Just thinking out loud.

1)If you can get the copper line out with the nut intact, try pressing a 1/4" ball bearing through the nut to open the brass back to 1/4"
2) make a new nut on the lathe

No flaring there, the taper of the nut has compressed and swaged down around the tube.

The ACE Hardware store in the neighboring town has those.
I was looking for something else and staring at the little plastic boxes of this and that when I stumbled onto those.