Several of the key players at NR in the early days were Catholic or were converts to Catholicism. They included Wilmoore Kendall, Russell Kirk, L. Brent Bozell, Jr., and Frank Meyer (converted on his death bed).
Buckley wasn’t a “conservative Catholic” - "In fact, Buckley was not a conservative Catholic, in the religious, doctrinal sense of the term. He opposed the wisdom of church teaching on social and political issues. He favored decriminalizing drugs and wrote for Playboy. For a time, he defended southern segregationists and supported birth control. In other words, Buckley was not the intellectual godfather of Ray Flynn or Bob Casey, Sr. This is not to suggest that Buckley was a liberal Catholic in the religious sense. Besides his lifelong opposition to socialism and communism, he opposed legalized abortion and opposed “Playboyism.” So what was Buckley? He was an idiosyncratic Catholic. On political issues, he took conservative stands, as well as a few liberal ones. As an example of the latter, he wrote a book arguing that the state, not the free market, was better able to nurture citizenship and a sense of civic obligation. On religious issues, he was a mixture of both. His views are complicated. He called himself a Catholic and a libertarian. Go figure."