I think you are really asking how to verify the location of the event. This is more important than deciding which spelling to use. Scale and accuracy are important considerations.
Historical records identify where an event occured using a place name or description of the location. The place name may be very specific e.g. a house name or street address, but often is more general e.g. a parish, town and can be quite vague e.g county, district. A specific location can usefully be described using geographic co-ordinates to an accuracy of a few metres. Administrative units are better described using a polygon that covers the area of the jurisdiction, so that spurious accuracy is not implied. A gazeteer is essentially an index of labels on a map, which give the label name (e.g. a hamlet, town, region) and the central co-ordinate for the feature, and gives no information on the boundaries of jurisdictions. A critisism of the 'Place Authority' mentioned by A C Proctor is that it does not resolve the limitations of the gazeteer. A better solution would be to map historical jurisdictions. An example of such research is the A vision of Britain website
Current maps, including Google maps, Bing and others can be helpful. Taking the Spilleren Farm, Meløy, Norway (1782) example, I can locate Norway and the island of Meloy. Wikipedia has an article on the modern jurisdiction of Meloy (a municipality) and gives co-ordinates 66°47′17″N 13°40′33″E. So, I am reasonably confident that this is the general area. Finding the location of a farm is more problematic as feature this small are often only named of large scale maps. Names of farms can persist for long periods, so may be included in a local gazeteer or maps. You should not assume that the place name is no longer in use before looking at a map of appropriate scale.