Will This Setup Work ?

I've never had a tank that big, but IMO, I don't think it will work, it all depends on the fish and the size of the fish. You are going to need a loy more filtration to keep them though.

Not too much.
IMO you prolly should just forget about the RTBS, it will prolly get picked on.

Hello.

I personally think the only problems you might have is the severum and the GT.

The Redtail and the loaches should be fine. Loaches get quite big and the red tails are known for there nasty temperment. I doubt that the terror will bother with either of them. I could even see the Red tail giving the Gt a hard time for a while when they are both still young. Until the GT grows up and reaalizes that it is a GT. Then things will calm down. But........

It will all depend one the personality of the GT. Some are quite nasty and some aren't. If you end up with a relatively doscile GT, you could probably even get away with throwing a decent sized (in relation to the GT) severum. Severums are mid to high range tank dewllers and will avoid the terror for the most part.

Supply enough caves for the RT and Gt and some tall plants for the severum to use as cover and you should be ok.

first off how big are the fish?

SCOTTMACD has a good point about the GT, it could terrorize the whole tank or not it just depends on what size he and the rest of the fish will be, and the order you put them in the tank. maybe the severum may get picked on but he stay near the top of the tank so he should be fine IMO.