I know the HF was 8 valve so you might be confusing the STD with that. I've never seen any solid evidence to say that STD was 8 valve though.

The "Cylinder Head" pictures on hondaautomotiveparts.com have the same image for the STD and DX engine, so I don't think STD is 8 valve.

Also "Valve-Rocker Arm" both lists the needed amount of valves as 8 intake 8 exhaust for both engines. So once again I don't see it being 8 valve.

The cam shafts are different part numbers also, perhaps different cams.