No, the Thickstun covers just go on top of a normal flathead heads. Dress-up parts, mostly.

Ardun was an overhead valve conversion for a flathead. New ohv "hemi" heads with their own actual valve covers. They had a "modern" design intake manifold with 4 intake ports, and 4 exhaust ports in the hesd as well. Huge increase in breathing for the engine, increasing horsepower. That led to multiple carbs, superchargers, etc... Here's what an Ardun conversion consists of:

Ardun flathead engine: