Check the points first. My 3000 had been the easiest starting engine I own, when suddenly it wouldn't start, just ground round and round. When I checked the points they were SHOT!! Replaced them and all is well again!
Not like a Plymouth slant 6 I had. It would run with a knot on one of the points as big as a pin head. It finally got to running so bad it wouldn't pull it's self up a hill in 3rd, almost didn't make it in 1st. That's when I finally took time to replace the points. :-)