well take this for a reason
Corydoras are bottom dwellers, in which the bottom of the tank gets less oxygen, with the already high amount of fish you are going to have the oxygen levels will be quite low down there. Sure you can try to raise the oxygen by making the surface more turbulent but then the gourami wont be able to succesfully make a bubble nest with all the strong current
Second corydoras barbels are sensitive to water conditions, nitrate being one of them, you will need to keep the nitrates below 20 for them to be happy as a high nitrate level will damage there barbels. With a largely stocked tank the nitrate levels will be high and unless you are willing to do many water changes, there barbels will deteriorate.
Cories in a small tank, might work if you are willing to do a lot of stuff on it, it might work, corydoras in a small tank with other fish that overstocks the tank a bit, no.