I take it you don't have an exact birth date. Where exactly did he die? Any chance there is a surviving state death record, obituary, or church record? It's hard to do much without the village name in Germany where he was born. I didn't find a census record online in either Ohio 1850 or Kentucky 1860, but I could have missed it. I don't have a John Dahling or Elizabeth Kampf in my records, so that perhaps means they weren't from Vellahn parish in Mecklenburg. Dähling (with some variations) seems to be a frequently occuring name in Mecklenburg. Would love to here if you do find anything.