You should be okay at 300 lbs spring pressure. Make sure that you have plenty of oil pressure as well as oil flow to the top end.

For a lower speed street engine you might consider grooving the #5 cam journal to provide full time oiling to the top end. You don't want to fill the valve covers up with oil on a race engine, but on a weekend cruiser that doesn't get wound to the redline very often the extra oil can be a good idea.