Tank Mates for a Gold Saum in a 125?

I have a 125 that has 4 oscars, a Chocolate Pleco, and a 4" Gold Saum in it. The oscars are leaving to their new homes this weekend. My husband and I have been looking around and he seems to like (he is just getting interested in my tanks) Festae, Salvini, Convicts, & Belt cichlids.

Would any and/or all of these work in this tank?
How many?
Any other suggestions on Cichlids?
What dithers if any?
Will the pleco be ok?
What kind of decor?

Thanks