There was no Sunbird in 1995. They switched it over to the Sunfire in 95', and used the 2.2L and 2.3L engines.
As for the 3.1L question though, as long as it was in a Sunbird or Cavalier between 89' and 94' it should pretty much bolt right up perhaps with the exception of a few sensors depending on the year. GM used the engine in a whole bunch of other cars during that era as well, and I think they would also work, but would require a few more modifications.
If, however you are talking about the updated version of the 3.1L, the 3100, released in 1995 then no, it wouldn't work without some pretty major modifications. Wiring harness, ECU, etc. Hope this helps!