If you are doing spectral comparison, you can eliminate a lot of absorbance
with the reference and zeroing. It's ok, but not great, even at these
wavelengths, for spectral comparison. Even for spectral comparison, you
have to be careful.
I use the values given in the books as guidelines. The minimum wavelength
can still vary, depending on a number of things (instrument, buffers if any, etc.).
Sorry, but for me, it is still best to run the method and see what you get.