Looks like a great project. I'm pretty sure that all 51-54 288's and 327's were painted gray from the factory. Only the 359 was painted a bronze color. Green or teal on a 51-54 block would have been a non-factory repaint, or the engine was from a 48-50 car. Those years were painted dark green like the older Packard engines.
The teal is definitely a factory color, I've only seen 1951 engines in grey. Including a 51 Patrician I did work on. I did run the engine code on the Packard info page, and discovered that it is a 359 block as well.
