Seems high, but if there is shop rate is close to the $100 mark, might be about right. Also, if it includes parts, it would probably be closer to the price they are asking. If they are doing everything correctly, they will be putting on new valve cover, timing chain cover, intake, and water pump gaskets. I would think that they would be replacing the timing chain as well as the cam bearings to do things right. Remember they will have to remove the radiator, so new coolant as well. Also, they should be tuning your carb to the new cam as part of the deal. The labor to remove all the part clean and reinstall them adds up quickly. Most shops will warranty their work, so factor that in as part of the service.