Ernie Colón drew at least five pages at Archie in 1960. Maybe he did more—Archie put out a lot of comics at the time that I haven't read yet—but so far I've found his work in two issues of Archie's Madhouse. He drew "Stamps for Teens" (a two-pager) in #9, Dec/60, and "How to Read Tea Leaves" (three pages) in #10, Feb/61. His inking line is the giveaway, but the cheerleader and cartoonist stamps show his pencil style best, I think.
These issues fall in the Madhouse
which Sy Reit, as far as I can tell, is the sole writer. (George Gladir
would take over as sole writer for some years, although the editors
some Reit and Gladir stories for a few issues during the changeover. In
Seventies a number of writers, including Frank Doyle, scripted
and Colón are connected elsewhere in that both
the Harvey characters—Reit created Casper the Friendly
Ghost before Casper was
a Harvey character—but more closely in that together they did
classics-type comics stories for Boy's
Life such as "The
Legends of King Arthur" (Aug/92).