The Argentina Y’s had the 289 firing order but like John says, the Y would need the cam blanks to make this happen. I'm with John on this one, “If it aint broke, why fix it?”. The Argy Y’s also had a different valve orientation in the heads which would be the predominate reason for the firing order change. The U.S. Y-Block intake manifold is specific to the firing order it already has and based on previous experience, the Y is sensitive to flow reversion and especially at the #1 and #2 cylinders. A change in firing order would need to look at the intake tracts closely and insure that two cylinders on the same side of the carb are not being fired consecutively.
Here’s a couple of past threads regarding some of the discussion on the Y firing order and intake runners.
Firing Order Discussion Intake Runner Discussion