Integrated tube amplifier: 4 ohm or 8 ohm connection?

Both can be tried.

@ 4ohm and 85db speaker spec's, my bet is the 4ohm tap is going to be best for your amp. 

Thanks :)

Definitely try both. Perfectly safe and reasonable to do.

Cool speakers! And as said above always try both.

Nice speakers! The maker should have used bases like the Bang & Olufsen Beolab 5.