Is there a way I can disable the Original darkrp hud with a function like it does for the base hud?
No because all scripted HUDs are referenced to as the same element in the hook you are thinking of and because that would be highly inefficient. You would be better off modifying the HUD/Derma skin directly to suit your needs.
Well you could do this,
But this will fuck up every paint out there!
just comment out the function in cl_init.lua temporary obviously