Wrong flex line?

I find it difficult to believe that welded tab would be different for the different brake assemblies the chassis might receive later down the line. I never saw hoses on any vehicle that didn't have some type of positioning fix. My best guess is you have the wrong lines in hand.
I would first find out what is correct for K-H lines, then decide do I create flats on these hoses? whittle the tab opening to round? buy correct hoses?