Just today I was reading an article on C2 Corvette brakes by a guy recognized as a genuine authority. He commented that silicone fluid is prone to making and holding tiny bubbles when agitated. They will remain in the fluid and adhere to the metal surfaces so they will not migrate to the bleed valve. For that reason he recommended a very specific process for adding silicone fluid to the system. I'm including a link to his article.
I still think 550 PSI is too low and the fact that your MC stroke is bottoming out likely means one of two things. Brake fluid is not compressible, so if there is no air in it your system the MC must have too little volume for the calipers. If your MC is properly sized for your calipers, there must be air in it that is compressing to a smaller volume before the stroke of your MC can go above 550 PSI.
CRG Technical Article - Master Cylinder Rebuild