To be "perfect", the large positive (+) cable of the remote control harness, nor both large cables from each side of the starter solenoid were black colored insulation, not the red depicted. The terminals of the remote control wiring harness were however stamped with (+) and (-).
The starter mechanism, which is separate of the starter motor, does have an arm which swings a small amount horizontally to engage the flywheel ring gear on the 1955 model (also seen on 1956 Mark 30E, 1954 Mark 50E, and 1955 Mark 55E). Although the service manual does have another diagram showing the positive ground, when compared, they only differ in that (as was pointed-out above) the wire leads attach to terminals on the "swing arm" starter's lower end cap, and that the remote control large cables are reversed as to which terminal of the battery they connect to. I probably can answer any questions, but please post them in a thread, as I seldom login, so it may be quite sometime before I could respond. E-mails are welcomed, but posting of our business e-mail may not be wanted, but if allowed, it is: firstname.lastname@example.org
Joe Poole, Jr.