I have a similar problem - a death between 1851-55, and have not found anything so far. The area where the death I'd like to pinpoint occurred was Fearn, Easter Ross, which was a Free Church parish at that time. The church records for Fearn are at NAS at CH3/962/8 but I don't think there are any deaths noted as far as I remember. Also the MIs for many Ross & Cromarty areas are not published - not sure about Knockbain, as its in the Black Isle, for which there are some MIs, but there is nothing for Easter Ross. See:...death notice between 1851 census report and 1855. he shows as robert wilson aged 35,in the 1851, at knockbain,ross & cromarty...
http://www.highlandfhs.org.uk/HFHSMIAllVolumes.asp
http://www.highlandfhs.org.uk/HFHSGrave ... Search.asp
Best wishes
Lesley