Recently, the Library of Congress posted on its American Memory Project website the 1908 revised Cope-Carman maps of the "Atlas of the battlefield at Antietam" showing the position of troops at various times during September 17. This revision is posted here as the first map image on the left--click to enlarge. The Library had posted the earlier version of the map series--the 1904 series--on its website some years ago--this is posted here as the second map image--click to enlarge.
Both map series can be examined at the Library of Congress' Map Reading Room but the online versions are as adequate as an in-person view.
So how have the two maps depicted action in the West Woods between 9 a.m. and 10 a.m.? Here are some observations.
1) The most significant revision is that of the placement of the 69th Pennsylvania from its 1904 location between the left and right "wings" of the 72nd Pennsylvania to further north between the right of the 42nd NY and the left of the 106th Pennsylvania. (Why the map continues to break the 72nd Pennsylvania into two wings is a mystery--I would certainly like to find something in Carman's papers that explains this.) The repositioning of the 69th brings Col. Joshua T. Owen's official report into line with the 1908 alignment. He writes: "As the brigade reached the top of the hill [marching east to west the brigade crests the Antietam Ridge about 100 yards east of the Hagerstown Pike and in clear view of the Dunkard Church], I noticed many of the regiments to the left of Sedgwick's division falling back in great confusion...[this would have been the 125th Pennsylvania pulling back from their position just to the west of the church and which is marked on the Cope-Carman map as leaving that position around 9:20 a.m. ]. ...The Seventy-first Pennsylvania Volunteers...was posted on the right; the Seventy-second Pennsylvania Volunteers...on the left; the One Hundred and sixth Pennsylvania Volunteers...on the right center; and the Sixty-ninth Pennsylvania Volunteers...on the left center." This narrative, applied to the 1904 map does not jibe since it depicts the 69th further south and sandwiched between the two wings of the 72nd Pennsylvania. With the 125th Pa. "falling back" and the 69th positioned further north, the 1908 map shows a much different view of the action as Anderson's and Kershaw's brigades swirled around the 34th NY, just north of the church, the split winged 72nd Pa., aligned on the Hagerstown Pike, and the 7th Michigan straddling the fence between the clover field (now part of Philadelphia Brigade Park) and the West Woods.
2. The 42nd NY is shown in the 1908 map to have at least refused its left in order to meet the onslaught of Barksdale's Mississippians--a much better position than depicted in the 1904 series--although the results remain the same.
3. The left of the 15th Massachusetts is shown in the 1908 to be angled further into the West Woods than in the 1904 map and the 59th NY, which fired a fatal volley into its rear, is directly behind the 15th's left. The 1904 map places the 59th in an overlapped position with its right situated behind the 20th.
4. The 125th is shown to have angled its right (or is it depicted as "falling back"?).
5. Smaller adjustments--in the 1908 map, the 106th Pa.'s alignment is less north and south but slightly angled to conform the the 20th Mass. to its front. The 106th and 71st Pa. also have shifted in the 1908 map further north and directly behind the 20th Mass.
6. As for the Confederate positions, there appears to be just one revision, that is the alignment of Jackson's Division to a position along the Hauser farmstead fence line and immediately to the east of the farmyard.
 The map's full bibliographic title is: "Atlas of the battlefield of Antietam, prepared under the direction of the Antietam Battlefield Board, lieut. col. Geo. W. Davis, U.S.A., president, gen. E.A. Carman, U.S.V., gen. H Heth, C.S.A. Surveyed by lieut. col. E.B. Cope, engineer, H.W. Mattern, assistant engineer, of the Gettysburg National Park. Drawn by Charles H. Ourand, 1899. Position of troops by gen. E. A. Carman. Published by authority of the Secretary of War, under the direction of the Chief of Engineers, U.S. Army, 1908." Washington, Government Printing Office, 1908. Retrieved at this location.
 "Atlas of the battlefield of Antietam / Surveyed by Lieut. Col. E. B. Cope, engineer, H. W. Mattern, assistant engineer, of the Gettysburg National Park. Drawn by Charles H. Ourand, 1899. Positions of troops by Gen. E. A. Carman. Published by the authority of the Secretary of War, under the direction of the Chief of Engineers, U. S. Army, 1904." Washington, Government Printing Office, 1904. Retrieved at this location.