Ok, let's see what's up with this set...
174 Atk / 174 Atk / 252 Spe. That's the spread you posted. Assuming you meant that, essentially 348 Atk / 252 Spe, which obviously isn't possible. Even if you meant SpA for the second 174, the total spread adds up to 600 EVs, which is impossible since no Pokemon can exceed the 510 EV cap.
Next thing...you're splitting Nidoking's attacking EVs for exactly what? Assuming that you could get 174 EVs in both Attack and Special Attack, a neutral natured Nidoking with the given spread reaches 263 Attack. With Life Orb accounting a small boost to the Attack, it would roughly have approximately 341 Attack. Rather tame compared to the mixed Hone Claws set up right now, which reaches roughly 388 Attack after the boost. In addition, with Hone Claws raising accuracy, that Nidoking can use high attack, poor accuracy moves like Blizzard, Fire Blast, and Thunder to inflict more damage than your proposed set.
As for your last move, yes, Poison Jab does get boosted, but Poison-typing isn't great offensively.