here is the trick I use on my pc. Go to musiciansfriend.com find a flat, dececent image of the bass with the configuration you want. copy the image, and go to "paints". paste the image, and make a line going through the center of the pole pieces. make a separate line going through a reference fret (i usually use the 12th). after you have those 2 lines, make a line along the centerline, connecting them. next re-paste another pic of the bass below the first one. no cut out the line, and line it up with the frets at image 2. drag it across, until you find the 2 frets that match it the closest. right down themm (ex. distance from 12th fret to neck coil = distance from fret 7 to fret 14. btw, those 2 frets are guesses, not accurate) after you know that, go to
www.fretfind.org/2d/standard.php and type in the scale you want (another plus about this method, is that you can easily do different scales with the correct position). look at the column that has the distance to the previous fret. add up the distances from fret A to fret B, and then you will know the distance from the 12th fret, to the pickup you want to install.
p.s. i think i have the 70's location saved on my pc. i will do a little browsing my files for you.