It would help if I paid attention to the capacitor part number and AIM sheet you cited, LOL.
I've no idea why they show different locations. I know on 67-8s they're all the same regardless of AC, and have the additional capacitor at the coil. And it doesn't seem the AC harness to the horn relay below, would pose any interference. Both sketches on that sheet look odd to me, as I thought the capacitor always screwed into the regulator base at the radiator side and not by the harness connection as they show. Can't make out the sheet revision note either.