If you like barbs, you should be able to get away with the stock I suggest so long as you've got excess filtration.
Try this, 6 Green Tiger Barbs, 6 Rosy Barbs, 6 Cory catfish and a BN pleco. You may be able to even add a few barbs if you really want to stretch it. Going by the "rule of thumb" this tank is overstocked, however the rule of thumb only applies to small fish, so you should be set.