Pulling 522 stroker from 1970 Swinger Help please

Bernie Schaknowski said
Good question, I’m not 100% sure it’s the chain. It absolutely could be a problem with the cam drive gear. Either way I’m sure it hit the valves so it’s gotta come out. Correct?

why not pop the plugs out and pop the valve covers off?
this way you can turn the engine by hand and see what the rockers do