I have made several posts regarding my rough running 1954 stock Merc and am wondering if it could be a timing chain issue.  I have zero experience with timing chains but have a basic understanding on the function.  The engine was running good, I lugged it out in second gear as I was pulling into my driveway, killed the motor and it sort of "humped up" like they do when stalled.  I have diagnosed and repaired/replaced all of the normal tune-up stuff.

What are the symptoms of a jumped chain?  And, more importantly, how can it be checked without an actual tear-down visual?  I have a good, old-timey, mechanic working on it now but he has limited experience with Y Blocks.  My pea brain says to crank to #1 TDC and then look at # 1 intake and exhaust rocker arms.  Please don't laff - I've never been in this territory!  Car has been down for over a year and my frustration level is to the moon...