6th generation: Hiram (Herman?) William Hopen. (my ggg paternal grandpa; John William Westphal Hancock's maternal grandpa)

This photo of the headstone and the death certificate that follows are slightly off the information on familysearch.org.  They both have Hiram as his name and not Herman.  In th 1900 Census he is listed as William H. Hepen/Hopen and his age as 39 which would give him a birth year of 1861. The headston below shows his birth year as 1859 instead of 1856... so there is work to be done.  There is a 12-page document saved on his page on familysearch.org that I want to read to see if it has any more information and if it clears up these inconsistencies.