If you can get the original profile of the cam, you could check the opening and closing points of the valves using a degree wheel. Otherwise, remove the cover and check for an offset key or a wide slot in the cam gear.
As for timing, the distributor would have to be retimed to the correct marks on the crankshaft after the cam timing was altered.
4" sleeves are real common in M engines. I doubt that the cam timing has been changed unless the person you bought the M from was using it as a puller.