You have been told to find exact TDC, are the heads still on? If so, You need an insert/positive stop to install in place of the spark plug(w/#1 safely before TDC say 90deg), then
roll the engine easy w/all the other plugs out up till it just stops. Mark the degree wheel Then roll counterclockwise till it stops again, halfway between that point & the 1st mark
is it-TDC. You could(& should) do this on the damper also to make sure it is marked correctly, or if the ring may have slipped.
