Actually, according to 5th edition rules, if you are using an older model you may use the base that came with said model. I'll look up which section it's in when I get hom tonight.
Now if you were using it in a tournie you definitly wouldn't score very high on sportsmanship points!!!
Adeptus Astartes Commandments
1. Thou shalt not replace the Librarian's staff with a magic wand.
2. Though shalt not refer to thine brethren, whom the Emperor has dictated be armed with an incendiary weapon, as a "Flamer" constantly. For this has been proven to lower morale and cause strife within His Most Holy showering facilities.
3. Thou shalt not follow a Librarian around thinking, "Can you hear me now", repetitively in an attempt to drive him insane.