It's not the overhead. It's the forward dash with an overhead. You can dodge the neutral overhead, but can't dodge the dashing one. If you get hit, don't spam dashes on an Orochi - he's going to repeat it until you're dead. Just block/parry something first and then do your thing. Please note that if you start blocking, you should expect the 2x top light/zone attack mixup and guard breaks.
I'd say that the best way to reset the situation after being hit by an orochi is to block right (the zone attack is faster) and immediately get ready to block high and tech the grab while slowly moving to your poking distance. He literally can't touch you then unless he does something with feints.