This adapter is to get the fluid into the caliper right? I just bought brass fittings with inverted flares. Apparently there are IOS and double-flare types, and after finding out about them, I reliazed what I had done.
My guess is that you just screwed the hard line into the caliper. Just doing that doesnt provide a seat for the brake tube. Mine leaked right away at first when I did this and I went to the brass fittings. That tapered hole you mention is the flare, when tightened down, the tube should fit snugly against that.
I don't remember what the stock lines for the new caliper looked like, I left them hanging at the junkyard...
Email me, I will try to take a picture of this thing tonite.
Owen