The problem in your use case brother is you're running the international phone which has an exynos processor, and the U1 Rom is running on Snapdragon hardware which was issued in the US. Your model won't run the US rom it's for a different hardware.
That being said, why do you want the US rom? What is it that isn't working as you would prefer with your current rom - because there may be a more optimal configuration amongst the many options on that internaional device which you could change your CSC to fairly easily with a couple Samkey credits - that will let you do whatever you're wanting the US ROM to do. I've heard people have been using the Indonesia locale 'cus it has native call record... Perhaps US English set as default language in your device and keyboard + a different CSC will accomplish what youre trying to do anyway. Good luck!