I need to find a suit with more length for his height. He's 6'3", 180#, waist size is 33.0 inches. other measurements if needed are: Chest 39.5 inches, hips 38 inches. In seam 32 inches.
I'm afraid that's going to tough fit. Normally, I'd recommend a 58 based on his height, however, this will be be somewhat baggy. This is a general issue with a in that the suits scale proportionally based on a "standard" body size- and if you vary too much from these you'll end up only being able to fit one of your dimension but not the other. There used to be one company that made Medium/Tall racing suits- these were very popular, but they inexplicably they quit manufacturing this size a couple of years ago and I haven't come across anyone else that makes something similar since. The only other option for a perfect fit will be a custom suit. We offer these through Oakley,but they are somewhat expensive.
That being said, in a standard one-piece suit I'd recommend either a 54 or 56. The waist difference can be mitigated some with the attached belt, but I'd expect it to be a bit big all over- hopefully not enough to be uncomfortable or look badly.