Aquascapes inventory is ridiculously inaccurate. You would have to actually call them and confirm before you bought them.
Yesh Crenicichla sp. 'tapajos II' /sp. 'cobra' are the same. Its generally more widely accepted to call them sp. 'tapajos II' though as there is no confusion then.
They will indeed get in the 12 to 14" range, and are quite impressive pikes when full grown. They can be a tad bit aggressive though sometimes.
Check with Aquascape as was mentioned. Possibly Shark Aquarium might have some. Aside from those two you will just have to look around and hope. They pop up every now and then, and some times random members will have some for sale.