Hi, Just thoughts:
Perhaps a search of City Directories - or the time frame around 1975 -eg Henderson / Wigleys - Criss Cross Directories - name to address - address to name - may show adult living at an address at the time - may help determine if Edward Elwood King CAMERON passed away in 1975
Public Libraries may hold newspapers in their collection. Some libraries may index Obituaries -
City of Winnipeg - has a number of Cemeteries - perhaps contacting them- will see if there is a burial . and if not - they may be kind enough - to search other burials/ cemeteries. for a date of death
Funeral Homes - Search Winnipeg Funeral Homes online - If they were not the ones making arrangements - may be able to offer - help -
Online White Pages Directory - for the son - There are 13 listings
Just random thoughts - that have worked - at times.