1979 55 hp Evinrude shut down suddenly

[Aeroflyer]

My 1979 55 hp engine 55975c has been running well this spring and summer. It is a boat that had not been run for 15-20 years before I acquired it. It had an emulsion tube gasket missing in both carburetors. That problem was discovered and solved through this forum. Since then, it has run dependably until a week ago. I had run hard upriver for about 20 minutes. When I began to pull the throttle back to swing around to a fishing area, the engine shut down like the key had been turned to off. Since then, I have not gotten any spark. I'm assuming the power pack failed or maybe something under the fly wheel. The kill switch system doesn't seem to be the issue. Looking for ideas.