Tom, Mike Riste's book does not list Shaughnessy Heights as a course that Macan had any involvement with. Mike's research is exhaustive and I think it can be relied upon. Macan, of course, did design the new Shaughnessy course when they moved in the late 1950s.
Interestingly, Wikipedia notes SH was formed in 1911, opened 9 holes that year and the second 9 the year after. And then it credits Macan with the design, citing Cornish, Whitten as the source, a copy of which I do not have.
Regardless, it is not true Macan was the original designer, he did not arrive in Canada until July 19, 1912 (source: Riste's book).