I've got a similar size tank , just a bit smaller I'm setting up. I am considering a solo,salvini but also think it may be a bit small for even 1 once it's grown up.
Salvini are very aggressive so I think a tank this size won't work for a pair especially if they don't get along and start brawling.
If you scape the tank nicely and have 1 nice salvini and possibly some larger tetras or livebearers it would look great, that's what I am considering doing anyway.
Another thing I'm thinking about is a pair of convicts or blue eye cichlids which should work in a tank that size.