
If you can't find his waist or feel his ribs easily then he is more than likely too fat, and with the short face and compromised breathing you do not want him carrying extra weight to make things harder for him.
You can not really say what weight he should be, as even in my breed where the size is the same to within an inch the dogs can vary by what weight is right for them, some being just right heavier or lighter and also how much they eat to keep their correct weight.
I would feed half the recommended amount on the bag of food if he is overweight as chances are he will actually only need between half to 2/3rd's, as I have rarely found any of the dogs I know or have owned need any where close to what the packaging says.
After a couple of weeks you should be able to see if he is loosing any weight and once he is trim you can adjust accordingly.