Can I win this appeal for a speeding ticket?

[arvad]

I was driving on US 101 North from San Luis Obispo back to Sac last night (saturday).
This was the first time I had ever driven on this road.
I was going 66 on the freeway, however the speed limit was 55 (as the cop informed me) - it was temporarily changed because of construction work. But there weren't any signs informing me of this. There was one sign that said the speed limit was 55, but it was a while back and I hadn't seen another sign that said 55 for at least 5 miles and the road changed so I assumed it was 65. I told him that too. He even claimed that I was going 74, when I knew for a fact i was going 66 because I saw the cop and looked at my speed. Then he told me he was "JUST" going to give me a ticket for going 10 over.

Do you think I have a case? Or because the speed was 55 and I was still going 10 over that I won't win this case? The officer said I could appeal, too. I asked him about it and he gave me a lot of info on how to go about doing it (because it was after he had already written the ticket).

Thanks.