Thanks guys. I took a Confrontation Kelt Centaur, removed his head and added the helmeted Gor head from the GW Beastman plastics box.
The shield is an old Empire 5th edition shield with the lion head shaved off. The bent spiral pattern struck me after several hours of agonizing over possible markings. I wish I had added two additional bends in the outer parts, but it still gives the spiral effect.
Compared to the 3 Citadel Chaos Centaurs I have in my bits box, this guy is huge.