Here's a partial answer to your question. I have the Dearborn engine release list through the spring of 1928. The first indication of an engine set up for RHD is December 5th 1927 with engines A1484, A1481 and A1496 so marked. By this time, the first frame with the three piece front crossmember and the single eye /single eye brake system, i.e., no external brake retracting springs attached to the frame and rear radius rods, no upsets in the brake rods, was obsoleted. I would conclude no RHD cars would have had the first system. For example, A1276 was release before A1031 on December 3 to Rouge Assembly. Both of these vehicles are matching #s. A1031 has the first system while A1276 has the second system, double eye / single eye. This system would be the only one in a very early RHD chassis. I have never seen nor heard of one existing. By Feb 1928, the third system was starting in production with the double eye / double eye system in some plants. This center ebrake system reduced the number of special parts required for RHD. Given stricter European standards for seperate ebrakes, I feel that the third system would have been used early on for export.
A second generation braking system in an early RHD would be very rare and worth seeing.