Wasn't this supposed to be Ken vs Scorpian anyhow? My problem with Ken is that his feats or abilities are next to non-existent so most of it is pretty much just theory and comparison base making it incredibly difficult to compare him to other fighters. The best thing is that Ken is powerful enough to contend with Ryu (although Ryu is obviously the better overall fighter as proven since they first began training together to the present day and also that Ryu has the better win record as indicated by him to Ken in SFIII).
So in my mind, Ken's feats would no less come close to that of Ryu's own.
There is no way to how ripping off someones head would equate or rival to someone destroying a ship within the ocean depths. Gouki's feats are vastly superior to Scorpian or basically anyone elses within the MK universe. It'd be far, far more plausible to see someone ripping another persons head off to them taking out a ship from deep within the ocean trenches or splitting a mountain into four pieces or sinking an island by slamming ones fist to the ground. That's not even close in comparison of powers.
However since the arrival of Ingrid as a Canon SF character, I do not now believe that Gouki as ridiculously powerful as he is would be able to rival Ingrid because of her status as a True Goddess and her feats that has been portrayed for her. From what is shown at this point, I would even argue that Ingrid is the absolute most powerful being in the SF Universe, even above Gouki.
Someone also posted earlier stating that Gouki cannot move as superspeed. I remember at srk.com someone gauged the speed of Ryu and Gouki in order to create that massive sonic boom shockwave when their fist collided showed a speed feat that was indeed super human or "superspeed" if you will. Guile's Sonic Boom travels at Mach 2 speed, indicating that you would need to move at a ridiculous level in order to dodge that, something that Ryu is even capable of however in Gouki's case it would be an even greater and higher level of possibility.
The real point here is that what Gouki has done with his feats (splitting mountain, sinking an island <---- Important factor with this feat is that he did this during Alpha 2, and his A2 version was weaker then Alpha Bison, plus no where near his later SFIII counterpart version, destroying the ship under the deep ocean waters) shows nothing that even remotely indicated he was in "Shin" Gouki mode, putting Gouki on a level beyond ridiculous because he achieved all of this without even utilizing 100% of his full potential.
"If" Capcom were to continue with this trend on Gouki's abilities by the time SF:5 arrives and if it's Post-SFIII's storyline, Gouki would be able to vaporize a planet if he went 100% because it's getting to that level of outrageous factor.
So it leaves me without question when you look at all of the evidence with no bias towards either character that Scorpian is nowhere near that of Gouki.