No. The K-402 horn itself is good down to 172 Hz before the axial length begins to approach 1/4 wavelength. The horn mouth itself is good down to ~40 Hz for directivity control. At that point, the wavelengths are 78 inches long, and the small mouth flange itself isn't significant. The Celestion Axi2050 can be used down to ~225 Hz. Roy's preliminary data sheet shows that he's crossing at 340 Hz, so you're in good shape without any tapers or "baffle step" considerations.
All righty then...wasn't really expecting an answer hence the smiley face...more just goofing on everybody....it's all good ...carry on