I would check out Lenzi's "Man from Deep River," it is considered to be the first film in the Italian Cannibal cycle, that Holocaust and Ferox epitomized.

Also, Jungle Holocaust as previously mentioned is a good pic. You may also want to check out Lenzi's "Eaten Alive." it's probably the worst cannibal film that he's ever done, and it reuses a lot of footage from other Cannibal films, but it's sort of interesting if you're looking for more stuff to check out.

Not a cannibals-in-the-jungle film, but I would check out Antonio Margheriti's "Cannibal Apocalypse." It stars John Saxon and John Morghen, and is really fun for cannibal film.

Lastly, I would recommend Sergio Martino's "Mountain of the Cannibal Gods." it's slow paced, but it's pretty cool, it has nothing on Ferox or Holocaust, but it's worth seeing at least once.

I haven't seen these either, but these are considered part of the Italian cannibal cycle, a good few of them can be found in Media Blasters "Triple Feature," box sets, that can be acquired online quite cheaply.

Emanuelle and the Last Cannibals (Joe D’Amato, 1977) (Trap Them and Kill Them)

Amazonia: The Catherine Miles Story (Mario Gariazzo, 1985) (White Slave, Forest Slave)

Zombi Holocaust (Mirano Girolami, 1980) (Dr. Butcher M.D.)

Anthropophagus (Joe D’Amato, 1980) (The Beast, The Grim Reaper)

Massacre at Dinosaur Valley (Michele Tarantini, 1985) (Cannibal Ferox 2)

Cut and Run (Ruggero Deodato, 1985)

The Green Inferno (Antonio Climati, 1988) (Cannibal Holocaust 2)