I'd remove the FMs because they don't fit. There's actually quite a bit of room in the mid/upper water column if you don't have to keep the SDs, for fish like angels, a pair of severums, Uarus, festivums etc etc. Not all together of course.
I agree with all peathenster said.
I would remove the firemouths, they seem an odd addition to a south American tank.
Silver dollars are nice but if it were my tank I would have a group if festivums for the upper levels, and maybe a group of giant hatchet fish.
Brochis splendens would be a safer bet long term instead of your smaller growing cory's.