its your distributor most likely, they are very common to fail. pull a plug, leave the tip in the ignition wire and ground the threads to a nut on the engine. have an assistant turn it over and see if you have spark. if you dont, most likely will be distributor. it is not you alternator, with the plug pulled and engine attempted to start you should smell gas inside the chamber or hear the pump turn on when the key is switched on. if you dont have spark, dont bother replacing the the coil it is never the problem, ive had one module blow, but it is very rare. more common than not the hall effects sensor in the distributor has shit the bed causing you to replace the whole unit. There will be two types of distributors when shopping for a new one TD42-u and TD44-u you most likely have the 42 as it seems all my B series heads take the 44. keep your core till you can compare to whatever one you buy.