In the 14 months since Kenosha’s Lennie Boresch Jr. turned 50, he has established himself as one of the top senior bowlers in the world. On Friday at South Point in Las Vegas, Boresch can take a big step toward possibly being the best Senior bowler of 2013. “Skyn” is one of four unbeaten players among the dozen left heading into the final day of the 2013 United States Bowling Congress Senior Masters. The other unbeatens are Dave Axon, Kerry Painter and Robert Brown. But...