I haven't seen any 47k or 470k multi-turn VR's. They must be ~15-20 turn, like these: http://ceemic.pri.ee/hardware/_trimmers.jpg
Usually they are 1k, 5k, 10k, 20k, 50k, 100k, 200k, 250k, 500k etc.
500k ohm is very safe to use.