For all you know, they’re not digitized, unless the Library of Congress has done it. You might have to do things the old-fashioned way (microfiche), at a library that has it (such as the LoC).
Old stuff from NR was indeed available online, but on a pay for basis. E-mail them.
The NSA prolly has all the info you need and more.
If you’re in Southern California, Occidental College and Whittier College have print copies of National Review in their libraries, but the sets are not complete.
Fred, if you’ll come clean out my garage you can have all my old copies.