No, not for a permanent home. Only time I would is for a grow out if the fish were very small (2" or so). And even then it would only be for a few months. The Oscar would need an upgrade real soon as they grow very fast.
That 90 would be ok if it was just the Oscar with no other tankmates. You would have to really stay on top of water changes as the fish grew bigger. Personally, I like 6 ft tanks for Oscars and then you could add other fish.
Agreed, that will be too much fish for that tank. The oscar, JD, and severum will likely all get along fine, but the oscar will dirty up that tank water pretty quick once it gets larger. Not sure how compatible the bichir really would be.