Seems people usually make a go of it with what they have (then get perturbed when others offer advice on positioning).
I'd say for a capable off-road drop set up, one should aim to get the hand positions at the hoods and in the drops at about equivalent to what they would be with a flat bar. Otherwise you're pretty far over the front. If it is a "drop bar mtb" for riding on the road, perhaps that doesn't matter so much. But generally, a shorter, higher stem is a better bet for converting most mtb frames for use in a dirt drop set up. YMMV.