Somebody did this already:
https://forum.blockland.us/index.php?topic=287076.0Unless i misunderstood what you wanted.
Alternatively, i can share something that i have on the slowburner right now:
Bot_Left4BlockWhich is an add-on that will add all the zombies from the left4Block original add-on (Rotondo's Gamemode_Zombie) to the new bot system.
So far what i have ported is the Tank, Witch and the normal zombies (which is actually one bot that has a varying speed and according damage).
There is a bug where they turn other bots in zombies like the default zombie bots, that turns the tank invisible (i think only the tank) but if you want you can try it out.
I have plans to finish this and make the abilities and looks of the zombies also work on players whom have the playertype set on them, but these days i find it hard to work on things due to all sorts of things going on.
So be warned if you use this, it might not work 100% super great.
I did not mean to advertise my half-assed stuff once again, but i felt you might be interested and this seems to be something i come back to every once in a while.