Nice, easy. I have some reddish gravel in my 150 that my oscar really stands out against, its made by Carib-sea and its a mixture of the Amazon and Redwood colors. Looks a lot like fluorite actually.
Its nice that you already have the sump. I'd look at something like a Mag 10 for a return pump, and three 300w Visitherm stealths for heaters. The good news is that quantity of water will hold a ton of heat energy so once its at temp, it shouldn't be too difficult to keep it there as long as the room temp is relatively close.
I really your ideas of a few oscars, but it does kind of clash with your other plans. First, oscars really don't like to let plants stay planted. Also, what jdub said, any small schoolers will be lunch in a hurry. I used silver dollars for dithers in my cichlid tank, which work well, but again will destroy any green in the tank.
Anyway, looking forward to seeing it set up..I'm jealous. Although I'd end up doing a big FOWLR setup for my puffer, a bunch of damsels and a huge mantis shrimp
. And if you need some large driftwood, I might be able to help out, I've gotten some nice stuff for my tanks and jdub's in the woods and streams around here. And its free!
