Simple napkin math, so you know what both shadows are you need to find how tall the High Roller is we will use X for this.
Im not 100% I set it up right but essentially 242 divided by 2'9" and that equals 88
Take 88 and multiply that by 6'3" and you get your Height for the High Roller
What I did their was I scaled the humans height to that of the High Roller dividing it gives you a number you can use to scale the height of that human to how it should scale to the High Roller, which is why I took 88 and multiplied it by the human's height.