Yes, you can do this legally. I need to know how many wires are on the old circuit and what colors they are. Also, is the circuit in metal pipe. If pipe, is it exposed at some point where can you read the markings and specs on it. The receptacle, does it stick out from the wall or is it flush with a cover like switches and receptacles in the rest of the house? If it's flush, pull out the guts and shine a flashlight to the back of the box. It will be stamped with a cubic inch number like "17 CU". I need that number. It's not a deal breaker, but I'd like to know what guage wire. Good luck.