In my experience dwarf gouramis are a bit more aggressive than pearl and you might actually find the aggression stems from the dwarf. I haven't actually kept them both at the same time so i can't be certain, but you have a nice big tank there and with enough plants there will not be any problems i am pretty sure of that.
Start with a single dwarf and see how it go's. If the aggression isn't a problem then maybe add another. Better than getting loads in at once only to find they won't tolerate each other.
Hows the flow in the tank?
One more thing, dwarf gouramis are slightly notorious for being a bit short lived due to inbreeding and disease (but there are people who have no problems with theirs), so i would definitely quarantine before adding to the main set up.