in aspect to other Balanced
75/95/95/95/95/85 - Kingdra - 540
100/110/90/85/90/60 - Swampert - 535
80/70/70/90/100/70 - Ludicolo - 480
You forgot Porygon2, a very good example of a balanced one, with 85/80/90/105/95/60 = 515. I've based my stat proposal (90/105/95/75/95/60 = 520) on him, since I like the distribution and the slightly higher attack stat on top, which I've switched to physical.
It seems like most everyone here is favoring the Special Attack stat against the Attack stat. Being Ghost/Fight I know it could go either way, but somewhat I like the idea of this pokémon having a good attack stat. This allows for choosing among different priority attacks (two of them with STAB), decent but not amazing STAB moves (Shadow Claw, Shadow Punch, Force Palm, Cross Chop...) and other possible and useful options, like elemental punches, or Aerial Ace, or maybe Zen Headbutt, etc.
Anyway, since the "Balanced" spread is pretty much going to win,
I'd like to convince you all to make this pokémon attacking stat mainly physical which allows for many interesting options, and doesn't have to rely in the boring Shadow Ball for STAB (it's a pity, but it's the only decent Ghost special move). Being special would give it exactly
two STAB options: Shadow Ball and Aura Sphere. Physical allows for more variety. I know Shadow Ball and aura Sphere are great moves, but having only them is boring.