I didn't use Red Chinchompas but I've heard some figures for Greys at the Ape Atoll tunnels. I believe it should be 180-200 exp/chin depending on your level. They are better gp/exp. A rough estimate based on the exp/chin, you should need around 18k chins. The best way to get the most exp is to try to hit 9 monkeys at once. They do respawn from where you kill them (where their bones are), but I suggest running away and back so they monkeys unstack a bit because if there are too many monkeys + bones on one space, they won't respawn. Watching some youtube videos may help you perfect training techniques there.