That may work but you really want the generator running on true Neutral. I always set neutral when we get a generator back from the shop. You would be surprised how far off it is sometimes. It’s more accurate to use a 6vdc source and a center reading millivolt meter but 120vac and a digital meter will get you close. Only then should you adjust the series field taps and compounding. It doesn’t hurt to check the quartering of the brushes either if you are having mixed results.