The set zoom should be doing as it states and sets the zoom, the function looks to be in the correction location with the correct map object specified. If you are still not getting it to work though then you should try setting the zoom on the set center function. Does this not work for you? Please let us know so we can check into this further if you still having problems with it.
It should not really matter how you implement the zoom. If you change the default values in the file then it should just use this value and would not be necessary to adjust it with the setzoom.