As we mentioned, you will probably want to avoid using the old fuel supply in the vehicle. Bad fuel can cause valve and piston issues if allowed to enter the engine. With a carburetor you can provide a gravity feed of fuel to the inlet, or plumb a temporary external pump to provide fuel to the carb. Be aware that the carb float could be stuck and allow excess fuel to enter the bowl. You can also pour gas down the carb vent tube to fill the bowl. Another option for a quick try at starting the engine is to shoot some starting fluid down the carb throat. However, use it sparingly because it can wash the oil film off cylinder walls if used in excess.