I can’t say for sure you’ll get exactly what you want out of breeding. Besides being difficult to breed (for a cichlid), as mentioned it can take a few generations of line breeding on your own to accomplish the color. It would be simpler to just get the morph you want if that’s the end goal.
That said, your tank won’t be sufficient for a single Oscar, let alone 3, unless this is a 250+ gallon aquarium. A 75 doesn’t offer much room for a 15+ inch beast to swim around in.