You can run it from anyplace that has 12 volts when the key is in the ON position and it will work. The bad news is the choke element will begin to heat as soon as there is voltage going to it whether the engine is running or not. The preferred way is to run it from an oil pressure switch that has 3 terminals on it. A normally closed side that brings the oil light on when the pressure is nothing or very low, and a normally open side that will close once the oil pressure starts to build up. The choke is wired to the normally open side so the choke element gets no power until the engine has fired and has began building oil pressure. Thousands of electric chokes are wired direct to some 12 volt source but imagine a cold day and the engine doesn't fire up right away. Now as long as the choke has voltage it is opening and an engine that began as just a hard starter has now lost the cold start help that a closed choke provides.
The 3 prong oil pressure switch was used on quite a few GM engines through the 80's and can be had at any parts store for under 10 bucks. It fits right into the oil sender tapping on your inline.
