There's correspondence from January 1954 between Adams and Paul Strand where Strand queries whether he should continue to use Kodak Portrait Pan (320TXP is the effective successor) developed in D-23 and Adams replies: "Portrait Pan film is very fine - perhaps the best quality for the kind of work we do. But the Super Panchro Press film is also fine and, of course, is more than twice as fast. With D-23 it gives excellent qualities. The only thing to do is to try it. I understand the new lsopan is a grand film, too. There is not much difference in scale between these films; it is chiefly a matter of speed and image-grain." The letters can be found
here on pg.81 of the downloadable document.