I couldn't find that list but the un-updated track and field news list of American juniors may not be hugely different.
It lists Ryun at 3:36.1, then Byers at 3:37.5/3:37.9, Webb at 3:38.26 and 3:38.50, German at 3:39.00, then Ryun at 3:39.3, Byers at 3:39.8, and Trautmann at 3:40.49. Jennings, Earl Jones(! the 1:43 collegian), Haney, Mudd, and Andrews (3:41.09) round it out.
Maton would have had to run this time last year to make the list (so, he was about 1.5 seconds off), but if he were 19 all this year, he'd slot in now with the sixth best performance and fourth fastest person. For 20 and under, he might still be top ten. For someone who was supposed to be fully developed in graduating hs at 19, he has improved nicely. 2.5 more seconds and he'll have an Olympic or World qualifier--I'd expect that next year.