SB-19 should work fine. With respect to your F3P, sounds like the shoe on the DE-5 got bent downward a little. My SB-800, which has a similar shoe on it (both flashes are probably made by the same manufacturer, just one with Nikon's name and electronics, the other with Canon's name and electronics), works fine on my F3P. That said, the contacts on the 580EXII might cause undesirable operation on the F3P, since the ready light contact is in the wrong place for the Canon flash.
Another option would be the SB-30. Small, flips down out of the way when you're not using it, and can do TTL flash with an AS-17 adapter on the F3P's regular accessory shoe around the rewind crank, or on an FE2, etc. Here's one mounted to one of my old F bodies via an AS-1 adapter.
-J