It depends on what your current happiness is. If you're at 100% happiness (happy citizens, production level: 100%), then yes, +73 population would result in -73 happiness.
If you're at 140% happiness (enthusiastic citizens, production level: 120%), then no, +73 population would result in -103 happiness. At this state you need 1.4 happiness for each population point in order to maintain that status.
Or, look at it this way: +73 happiness results in -73 demand for happiness, but -103 happiness to reach enthusiasm (otherwise written as "additional happiness" if your city is enthusiastic).