First of all, gotta start by saying that Scorpangel (undoubtedly the best Kang ever) told me
MIKECALDWELL gave him a lot of trouble with Shang. Not sure how they'd do in a best of 10 set... but I bet Mike would do very well.
SHANG
Has to do 1 of 2 things here- 1) get in Kang's face and jab like mad, or 2) morph into someone that can.
His triple skulls do a nice job of keeping Kang from air fireballing. His JK is boss, but can be anti-aired by Kang.
Let's not forget Shang can turn into 2 Kang-killers, Jax and Mileena. Mix up your morphs to keep Kang off balance.
KANG
Keep Shang away with a barrage of fireballs: air, high, low, and IAFBs.
When he JKs at you, anti-air him with a roundhouse or uppercut.
Be ready to adjust strategies if Shang morphs.
I'd say a 6-4 match for Kang. Shang has a lot of options (more than anyone) and if one thing isn't working, he can try something else.