I have a 400mm cube with a 70w Metal Halide lamp over it for my three rather spoilt freshwater puffers and four Otocinclus. Plants are Valisneria, Anubias, Hemianthus micranthemoides, Echinodorus leopard and Eleocharis acicularis.
Dose with 5ml Flourish Excel daily.
The Val is growing over the surface and obscures some of the light around the edges of the tank, and the puffers do not appear to need sunglasses when in the open water in the middle.
You 60w of T5s should be fine, your Ambulia will grow reddish at the tips with high light levels and the java fern should be fine. Algae may be a problem if you do not have enough fast growing plants to suck up the nutrients and outcompete the algae for them.
Ferts/C02 balance with high lights can be a tricky thing to get right - my tank can turn into an algae forest in two days if neglected :-?