The lathe is level, and Rollie's Dad's method agrees with this assessment. I have not adjusted the headstock.
1.25" 4140, protruding not more than 1.5" from the chuck, will show .0002-.0003" of taper over 1". This seems to occur regardless of depth of cut, feed, etc.
2" aluminum shows no taper, over 1". I don't have a longer piece of aluminum to test.
The difference between the two materials suggests that perhaps I am just dealing with material flex, I don't have enough experience to tell.
I realize this taper is pretty insignificant, for most purposes, I'm just curious about it.