Wildshape + Strong Jaw: Elephant, Common Gore

Hello all, wondering on the damage progression here. Elephant, Common is a Huge beast with a gore attack at a base damage of 2d8

Fine Dim. Tiny Small Medium Large Huge Garg. Col.
Gore 1 1d2 1d3 1d4 1d6 1d8 2d6 2d8 4d6

but that is however, "gargantuan" on the table. So as per the spell,

Each natural attack that creature makes deals damage as if the creature were two sizes larger than it actually is. If the creature is already Gargantuan or Colossal-sized, double the amount of damage dealt by each of its natural attacks instead.

Strong Jaw d20pfsrd

So then for a Huge Elephant with a Garg. size base gore, does it go to from 2d8>4d6>8d6? Or perhaps since it's already at one base size up by default, go to only 4d6?

Thanks much in advance, I couldn't find this in any thread in the search function.

Follow the FAQ. The damage dice in the natural attack rules (and the descriptions for Strong Jaw, Improved Natural Attack, etc.) are basically only examples, listing the most common version.
Thus, the gore is not "already at one base size up by default", it just doesn't follow the norm (probably to reflect that these aren't some small horns on a head but huge f&!#ing tusks).

So, the end effect is 4d8.

See the 2nd table listed under Natural Attacks for the damage dice progression.

Although, this doesn't make any sense to me, either, as the progression in the top chart is 2d8 to 4d6, but 2d8 to 3d8 in the bottom chart... (if you read the FAQ it says to go up 2 steps on the bottom chart for each size increase). I guess 3d8 is functionally equal to 4d6?