Hello Father David,
bevor I take an immigration date for this family I wait if Mr. Kock find these people in the parish records so we can see if the persons on the list of 1843 can be found in this family. We often have differencies between the name spellings in the lists but also with the informations in the census. The census was from 1900, more than 50 years after the immigration. So 1849 also could be 1843 in reality. But on the grave stone we have the correct date of birth which make it clear that we have the correct person. Only the immigration is not known sure.
Best regards,
Gunter