first what are the dimensions of the tank, i know its 4ft, and thats fine for them, but what are the other dimensions?
if i was you, i would take the 4 plecos to a lfs or something, because of how much waste they produce, but if you have the filter that can cope with it, then i dont see anything wrong with it, other than the size of them, if a they are 7-8 inches i wouldnt have them, but if they are reasonably small then they are ok. The Synodontis is fine also, people usually keep them with african cichlids in a big tank, so no problem there.
do you want to go for a species tank or a few of each species?
because if you were going to go for a species tank i would recomend Pseudotropheus saulosi, they have great colors, the females are orangy color and the males are blue with black stripes, maybe around 15, 10 female, 5 male?, ( im still not sure though, you might have to wait for an expert on cichlids, they know what they are talking about, im thinking of starting up am african cichlid tank also, and also i am looking for info, so dont take my word for what i said just wait for another post, there are alot of cichlid lovers on here and they know alot more than i do
