I'm guessing not custom (although the previous poster could be right about the fork crown being more common in custom bikes). It doesn't have quite as much detail as was typical of custom bikes around this time was made. I want to say Japanese but the campy drop outs point in a different direction. Still I believe that a few Japanese high end bikes were made with campy drop outs. There are folks here with more expertise who will chime in. Nice bike; it will be fun to rebuild.