I found an internet claim today that one Godfrey Isbell was buried in Sand Ridge Cemetery, Shelby County, AL, in about 1882. This is the first evidence that Sand Ridge Cemetery already existed in 1887, when John Henry Dabney may have died in a nearby steel-driving contest with a steam drill.
I also examined satellite images of Sand Ridge Cemetery. All the nearby roads show up as white. There is mention of a "white road" in at least one version of the ballad "John Henry."
Thus, it remains possible that Sand Ridge Cemetery is John Henry's resting place.