I had a few wild spruce timbers I had to deal with recently and here's what I did:)

plumb the timber in the center (will take out twist evenly on both ends)





plumb the ends mapping only the lines you need  (no sense of snapping too many lines or measuring off the center line)







I use the plumb lines on each end to establish the level lines on the other two faces if needed, and again only snap the lines I need ie. instead of a center line, I snap 4" off the edge for 2" M/T layout which becomes inside line of the M/T.