As near as I can remember, they never mentioned who had the job before Perry. The only mention I could recall of Perry before he was EIC was in 'All Shook Up' when he gives Jimmy an old typewriter and tells him that Clete Johnson took it all over the world for the DP before giving it to Perry when he was still a copy boy. Perhaps Clete gave it to Perry because he had become editor and was no longer writing?
Another episode which would have been a logical place for Perry to mention his predecessor was Stop The Presses. But, like Sue, I don't recall anything being said about it. Still, might be worth a look at the script.