Could your ancestor Belle have been Hiram's wife rather than Isiah"s? If Isiah was b 1876, he'd have been the age of Belle Conover McClure's children -- she was b. 1855 in Terre Haute. If the family moved to KY, that would explain why we haven't been able to locate info on her descendants.
There are however some other McClures listed for Terre Haute right thru the 1800s, starting early, including Nelson McClure b ~ 1814 d 1908 James McClure b ~ 1825 d 1906 Thornton S McClure b ~ 1832 d 1915 Alfred McClure b ~ 1835 d 1915