Canon EOS 650 telephoto lenses options

[Sgt.]

Recently purchased used Canon EOS 650 slr (about 1987 model) with a Sigma 28-70mm lense. I wish to shoot birds mainly and need some options on a used telephoto lense for this camera (Canon or other brand). It's an EF mount and want to be sure that autofocus and everything works with lense and camera. Looks like in the manual there's some 300mm options, but which one is best option?