If it were me, I'd just keep Meaty in there by himself.
The idea of having dithers for an oscar to chase around and liven up the tank is great---I very much enjoyed watching Triton's interactions with the tiger barbs I had in there---but in reality it will probably lead to problems (which is why I removed the tiger barbs).
I doubt that the danios would harass Meaty or do damage to him directly, but I can just envision him chasing them around and then injuring himself on something in the tank. Even if the setup is 'oscar-safe' he could still slam right into the walls of the tank and hurt his jaw, etc.
Of course, all of this still leaves you with the question of where to keep your severum.
I agree with SK in that having the sev in with the oscar in a 75 gal. tank might be pushing it, so I would never recommend that someone house them together like that unless they already had the sev and no suitable place to keep it. Yours is probably outgrowing the 33 gal. tank, eh?
BV