16 ohms speakers- 8 ohms output amp

The 8 ohm tap will work OK, but you won't get the most efficient power transfer. And depending on the speaker, you may not get the best (flattest) frequency response.

Why don't you look for an earlier model amp, like Audio Research, Dynaco, or McIntosh. They all have 16 ohm taps.

Not sure how many watts you need but the Eastern Electric MiniMax amp has 4,8, and 16 ohm taps, The M20 integrated amp also has 8 & 16 ohm taps.
www.morningstaraudio.com

The Hyperion HT-88 (18 watt KT-88 SEP) also have 16 ohms tap. See the 6moons review.

I bought these thinking that the Fertin 20ex would be an easy load since they are 100db and 16ohms. I thought of getting a 300b or 2a3 but now I think my choice is quite limited.