I segued to Evan Tanner, Matt Scudder and Bernie Rhodenbarr from mentions in the column or in the "about" section at the bottom of the page. I also read his stories in Alfred Hitchcock's Mystery Magazine and Ellery Queen's Mystery Magazine and picked up Ariel in hardcover from Arbor House.
Some things were harder to find. He mentioned once how he'd come to write a novel about a private eye named Ed London because he'd been commissioned for a TV tie-in for a show called Markham with Ray Milland.

Block and his agent ultimately decided the book was a better stand alone novel than a TV tie-in, so it became Death Pulls a Double Cross aka Coward's Kiss featuring a detective named Ed London. I eventually got to read that when a slim paperback was reissued while I was working at a library.
Block still had to turn in a Markham novel, so he sat down and wrote another. That became The Case of the Pornographic Photos (Belmont, 1961). Since then, it has been reissued as You Could Call it Murder.
A few Ed London short stories, along with many more short tales can be found in Block's One Night Stands and Lost Weekends. You'll also find a more detailed account of the transformation of a Roy Markham novel into an Ed London novel via meetings with Knox Burger of Gold Medal Books. Burger is also the guy who talked John D. MacDonald into writing Travis McGee books.
The book was not to be found in The Book Nook used book store of my youth, but I picked it up for just a couple of bucks a few years ago in a pretty nice edition.