I have the same lighting on my 55g. Here is what has worked for me:
Background:
Bacopa caroliniana
Rotala rotundifolia
Myriophyllum
Cryptocoryne retrospiralis
Crinum Onion plant
Midground:
Crypt wendtii, red and green
Crypt lutea
Anubias nana
Java fern
Foreground:
Echinodorous tennellus (i like this one better)
Dwarf sag
I have Ambulia, but it isn't looking good. I'm getting some Hygro Polysperma from a friend and expect it to do well. Its a fast grower. Hygro difformis (Wisteria) has done well in the past.
These days I get my plants from
Aquarium Plants. I've also used
Aquatic Plant Depot before.
Here are some links of places I haven't used:
Freshwater Aquarium Plants
Aquarium Garden
Arizona Gardens (they have a little higher shipping than most)