I recall reading somewhere that using an 8 ohm amp to drive 16 ohm speakers would limit them in some way. Don't recall the specifics of that article. Is that not true? Would appreciate some input on this question, too.
You might be getting yourself confused here because of the difference between tube amps and solid-state amps. Transformer-coupled tube amps allow to "tap" across the secondary of the transformer at different points to provide a better power transfer into the nominal impedance. However, the world is not going to end if you put a 4 ohm speaker on the 16 ohm tap or a 16 ohm speaker on the 4 ohm tap. I suggest to start by putting any speaker (regardless of impedance) on the highest impedance tap. On solid-state amplifiers this is obviously irrelevant.
Speaker systems have wild looking impedance curves anyways so the concept of "impedance matching" to the proper tap is essentially meaningless.
The answer to your original question is.....You really don't need to worry about it.

Dave.