[JhwShark]

Please post all results for both speeds:
HC
CO
NO

Good NO and CO means that you most likely have an OK cat and O2 sensor with A/F also probably OK.
Also, and more to your issue...high mileage cars can have issues getting a full burn. Using lowest octane in CA is best for smog tests. Since you have modest HC fail you are most likely not burning all the fuel. Low Octane has a flash point that will burn off more/most of your fuel during the engine cycle while higher octane may not burn completely in time...leaving some residual HC for the tester.

Drive the car for a good bit of time before the test as well.