If you take the votes Cassidy originally got, then add the votes the other two Repubs got, and consider that most of those votes will got to Cassidy, you should have a 60% - 70% take for him during the run-off.
Don’t count on Cassidy getting all of the Maness votes. Many Maness voters I’ve spoken to can’t stand Cassidy. They’d rather stay home than vote for him. There is a lot of animosity towards the La. GOP for backing Cassidy early on, even though there were two Republicans running. And Cassidy is considered a RINO, who also gave $2,000 to Landrieu’s campaign in 2002, and backed the Democratic candidate for governor, Kathleen Blanco.