I checked your personal page and it says your 65 currently has a 250 in it. They use timing gears, not chains. The V8's use a chain. Of course timing gears do sometimes break, especially the old fibre ones. I cannot imagine what a flywheel would have to do with it sputtering and shuting off. Sounds more like an igition or fuel problem to me. Have they checked the fuel pump, carb and distributor?