I'm not sure if this is of any help especially so long after your post but I believe I am descended from Kristoffer Larsen via his son Martin.
The Larsen's left Norway in 1867 on the Brig Atalanta. You can see further details inclusing a passenger lists here - http://www.norwayheritage.com/p_list.asp?jo=167&ps=58225
The spelling of names was anglicised and subsequently appears as Larson (the name I use today) and some fornames also changed spelling - e.g. Kristoffer became Christoffer as seen on the census of 1880.
Hope this helps