Lefever's Full choke in a 12ga generally ran about 4" long & had around .032"-.035" of constriction. Many full choke 12ga's of the era had about .040" constriction with a cone length of about 1½" or less followed by a 3/4" parallel. It would seem if anything the more gradual taper of the Lefever choke would give less deformation than the sharper cone of the parallel type.
It is though I believe quite unusual to find an LC Smith with a taper choke. Quite possibly the choke reamer was run too far down the barrel thus eliminating the parallel but still having the abrubt cone taper. As stated though to get much of a parallel much of the choke will be removed, so you will have to consider if this is acepable for your purposes. The original Win-Chokes at least had their entire choke within the confines of the tubes which ran to not much over 1½" & seemed to work well for most purposes.
