Yes those two can get xp together. IIRC the way you figure if you can group together is 1.5 of the level +1. So 51, rounded down, is 25 so 76+1=77 should be able to group with your druid and get xp.
I would recommend taking the druid to Blackfeather Roost and getting them several levels. Your mage will get aa xp while you are killing and the druids xp will jump leaps and bounds. I took a 54 monk there with my 73 shaman and had the monk 57 within a couple hours of casual killing, it just seemed to fly.
Another spot that would have fewer people there is Plane of Innovation. It still gives good xp and you can pull several more. I recommend getting a Journeyman Merc Tank for the mage and a healer for the druid and just pull several at once. I did this on the monk also and could pull 8-10 mobs and have the 73 J1 tank merc handle them without any issues. I did have an AE slow with the shaman though.
Try those two out and see how it works, they should both provide easy killing for your group. Then you may look at Sunderock or the Steppes to get a few more levels.
Reflection should be well timed rather than time-consuming.