With the addiction to "ground truthing" old maps to Google Earth in my list of habits, find 3 points of reference that are definitely shown on both maps and mark them. Usually road intersections are the best way, or other land marks that are not likely to have moved (yes, roads are moved, but you should easily be able to determine where that has happened and use another intersection).
Using a photo editor, overlay one above the other (must use transparency - which is adjustable) align the points (resize and rotate as needed). I usually place the newer map on the bottom layer at 0 transparency, and place the old map above at about 80% transparency (or 20% visibility ... varies with paint programs).
Now. after you have aligned the maps as close as possible, create a third layer. You can do your markup of your locations of interest on the third layer. Just put marks on the top layer (I like to use a dot - size relative to the area).
Now, make the old map layer invisible, the modern map fully visible (no transparency) and adjust the transparency of the layer you marked up so that you can see your marks, but not obscure the area belos. Now print out the results. Your new map will now have all of your locations you wanted to search on the old map placed on the new map.
Not as easy as guessing, but probably more accurate. If accuracy isn't important, you probably wouldn't have asked.