Dispersion Relation for EM Waves: Skin Depths in Good and Poor Conductors

[vanhees71]

This equation indicates B leading E by 45 deg. which is incorrect unless you're making an assumption that I can't fathom. B should lag by 45 deg. I, vanhees & the problem's statement all agree on this. So your error must have taken place ahead of this relation unless, again, somewhere there's an inconsistency regarding convention.

That's all correct. If you use my convention of the signs, i.e.,
\vec{B} \propto \exp(-\mathrm{i} \omega t).
Your case is for a good conductor, i.e., \sigma \mu \omega \gg \epsilon \mu \omega^2 or
\frac{\sigma}{\epsilon} \gg 1.
Then you have
k \simeq \sqrt{\frac{\sigma \mu}{\omega}} \exp(+\mathrm{i} \pi/4).
That means
B_0 \exp(-\mathrm{i} \omega t)=\sqrt{\frac{\sigma \mu}{\omega}} E_0 \exp[-\mathrm{i}(\omega t-\pi/4)].
This means the phase of the B field is behind that of the E field by an amount of \pi/4 (in the limit of good conductivity).