After seeing that picture of the part, I don't think it is a relative part of the 140 grouping. There is not even a place I can think of, it could go, especially related to the timing gear.
Memphis was very good. The Z parts were thin. I saw five DZ carbs, six 472 intakes, a 68 BV rearend, three or four 403 bell housings, one each 668 and 456 pulley, one endura bumper, a nice set of guages, a pair of non drip valve covers, and a early set of 69 Z exhaust, and that was it. For someone, that would have been something to dance about, I didn't find squat. I did pick up a good 367 starter, but not my date.
Thanks for finding that part. Maybe someone will know about it.