WD-40 can be used to clean it out. I would pull the motor out of the car first and then remove the carb. Spray it out really good with wd-40 and be sure to spray out every nook and cranny. To do it really good, carefully remove the high speed and low speed needles and clean it out. Be sure to open and close the carb while cleaning to get it cleaned out.

The important part is to remove the carb before cleaning. If you do have dirt in the carb, you do not want to push it down into the motor. While you are at it, it would not hurt to reseal the backplate and carb with some copper rtv high temp sensor safe sealant. And when you put it back together, install a new plug, clean out the fuel tank and replace the fuel lines. I bet it fires right up.