The perils of trying to stop the best high school football team in the state showed themselves right away Friday night at Finlay Field. Then they showed themselves again, and again, until top-ranked Sheldon found itself in the end zone for a third time before six minutes had ticked off the clock. Relatively speaking, the Irish’s frenetic pace took a hit from then on, but pouring rain couldn’t stop them from eclipsing their average in posting seven scores in a 49-14 defeat of Roseburg, their seventh straight win in the series. The Irish (7-0 overall, 5-0 Southwest Conference), who are …