Need to know how to wire an older Murray to new Briggs engine?

We have replaced a 10 hp Tecumaseh engine on a Murray rear engine mower with a 10.5 hp Briggs Stratton engine. We are having problems with the wiring. The headlight will come on, but the key switch will not turn on the engine. We keep blowing fuses while trying to see if the wiring is right. We need color coded wiring diagrams or just info about how to wire it. The Murray model number is 30500X92A. The Briggs engine model number is 28D707. Any help will be appreciated.