Whether overstock or not, depends on your filtration I guess? If you have no problems maintaining the water parameters with that size, I don't see why not really.
Orinos' growth rates are way slower than the Gators, eventually becoming feeders in no time. In fact the Gators will out grow your new tank pretty soon. May have better luck with Florida Gars.
Oh yeah it was modelled from his dead showa, I do remember reading your construction thread on koiphen some years back, very informative read. Great looking pond by the way :cheers: