I also agree with swapping leper for zombie or even another cabal

Leper Gnome is complete garbage in a control deck. It's used for rushing down your opponent.

And Excavated Evil isn't that good, I'd definitely use something else.

Right on. So what would you suggest?

Zombie chow is good, you might think it's counterproductive but it's not. Usually in a control deck like this, you don't really care about your opponent's health and you won't deal that much damage early anyways.
If you get this on turn 1, you literally make the aggro decks cry. And if you draw this late game when you really don't want to give the opponent 5 health, just don't play it.

About the Excavated, honestly it's for you to see how good it is. If it's not really useful, maybe you could use another velen's or another Cabal + Shrinkmeister

Also idk if you have Auchenai Soul Priest but usually it's pretty good in control priests.

Nothing counter productive about surviving the early game LOL.

but for those with less experience, giving 5 health to the enemy hero seems to be counterproductive

Oh i know, i'm just saying.

2 nova, 2 excavated evil, and 2 lightbomb seem excessive.

Imo:
-1 nova
-1 excavated evil
-1 leper gnome
-1 shadow of madness
-1 shadow word pain

+2 auchenai soulpriest
+2 circle of healing
+1 Acolyte of Pain

I would do this except for acolyte of pain

deck has too much draw already and chow has no drawback with auchenai