The ENTIRE fuel system needs to be drained and cleaned. 15 year old gasoline has formed lots of varnish. Before turning key try to turn the engine over manually to make sure it's not rusted stuck. If no provision to lube the cylinders/rings was done at the start of storage, it's conceivable that it has rusted in there. If it turns freely (plugs removed would make this easier), then spray some lube in each cylinder, remove the distributor and put in a priming shaft so you can turn the pump with a drill motor and prime the entire engine internally with that new oil you put in the pan. Once you've done all that, then you can put the ignition stuff back in and do as suggested above.