As noted, Lt. Col. Elijah Caines of the 14th Indiana wrote that his regiment came up to the stone wall "a short distance north (left) of where the markers were located," putting the walnut tree at the center of the right wing. Once the regiment shifted to the right along the wall, the walnut tree was near the left of the regiment.
When the 14th Indiana reached the hill, I figure the regiment had 162 men in the line (two ranks), occupying a front of 148 feet. That suggests the regiment shifted no more than 111 feet to the right, perhaps a bit less, based upon Caines' recollection.
Major William Houghton of the 14th Indiana wrote (in National Tribune, November 28, 1889) that his regiment passed the cemetery gate; Houghton's position being in the center of the left wing of the regiment passed (just) to the left of the gate. One can hardly be more precise in locating the regiment at that moment. Crossing the road at that point should put the right center of the regiment very close to the stone wall that ran perpendicular to the road, and which separated Ricketts' from Reynolds' batteries. I could also readily imagine that the stone wall served as a convenient guide for the 14th Indiana's charge to the base of the hill, so as not to disrupt the line. If so, said walnut tree should be at or very near that same wall at the base of the hill.
Charles H. Myerhoff of Company E, 14th Indiana (in National Tribune, April 24, 1890) wrote that the men overlapped the right of Ricketts' guns going down the hill, with the right passing through Reynolds' battery. That accords with Houghton's description, but one would suppose the 14th Indiana's right passed through only the left portion of Reynolds' battery based on Houghton's account.
"M." (Myerhoff?) of Company E, 14th Indiana recalled (in National Tribune, September 10, 1885) that one of the officers from Reynolds' battery inquired as to what regiment was passing. When the regiment reached the stone wall at the foot of the hill, they took fire from a stone wall to their left rear less than 50 yards away, presumably one running perpendicular to their line, which could only be the wall that separated Ricketts' battery from [Wiedrich's] battery further up the hill. The distance between that wall and the parallel wall separating Ricketts from Reynolds (calculated using Google Earth overhead imagery) is 230 feet.