Lugubris pikes are generally out, the tank is long enough, but really not wide enough to really be able to keep Lugubris pikes long term. A couple of Lugubris pikes are Crenicichla sp. 'xingu I' , Crenicichla johana, Crenicichla sp. 'venezuela' and Crenicichla marmorata are the more 'common' ones seen available, at least here in the states. So try to stay away from those particular pikes, as they will need at least a 100gal tank... Crenicichla cincta is another Lugubris pike that gets WAY to big.
Saxatilis pikes on the other hand still get large, but are more 'manageable' than Lugubris pikes. In a tank of your size they would most likely work out. Granted bigger tank would be better, but its possible. A few of the Saxatilis pikes are Crenicichla lepodita, Crenicichla anthurus, Crenicichla sveni, and Crenicichla proteus. Great pikes, full of lots of color! A lot cheaper as well when compared to Lugubris pikes..haha.
Dwarfs would DEFINATELY fit in a tank of that size. Scat mentioned Crenicichla regani, but there are a few others, Crenicichla compressiceps being one of the more common.
There is pike for almost every tank, you just gotta know which ones to aim for!