The wonderful American Conservatism: An Encyclopedia does not have an entry on Lefever, but it does have an entry on EPPC that mentions him. Here’s an extract:

In 1980, EPPC became independent of Georgetown. Under the leadership of its founder, Ernest W. Lefever, it achieved prominent visibility just as the Reagan era commenced. In 1979 the center was hailed as one of the eleven “bastions of neo-conservatism” in the United States in the national media. With its publishing and conference programs already in place, the center helped to reinvigorate the discussion of long-overlooked ideas in this new era of American politics.