Is it ok to take tylenol (acetaminophen) and aspirin together for a headache?

Sure. You can space them out or choose one of the combination products like Excedrin (aspirin, tylenol (acetaminophen) and caffeine). I also agree that Ibuprofen is a better choice than aspirin.
OK but. For headcahe it is better to space tylenol (acetaminophen) and Aspirin 4 hours apart. Instead of Aspirin consider Aleve : it's longer acting (up to 12 hours).