I'm currently reading it with much pleasure and interest. Ed McDonough for sure found interesting sources about the 158 project origins, and give a good view into the circumstances of his birth.
One step further, when mentioning drawings and ideas dating back to late 1935 - early 1936, would have been to point out that, in that era, it was not rare at all that great designers would carry out at home, on spare time, projects for advanced vehicles or racing ones. Merosi, Jano and, after the war, Busso did so, sometimes for important projects. Little wonder, thus that Colombo had ideas of the layout for a voiturette already in mind or on paper if he then managed to design the whole car over a few months from May 1937.
So far the only page that made me feel sorry is where Ed, who previously warned against legendary stories carried over from one publication to later ones, comes up again with the legend of a 3.8 litre Tipo B for the 1935 German GP. Not only it isn't true, but it would have been impossible, since the overall size of the enlarged engines would by no way squeeze into a Tipo B chassis.
This detail point having been made, I join Gary in recommending the book to everyone willing to know more on the 158/159 icon.
And, Gary, your Alfa books shelf is a nice one. Personally, I miss badly two of the books shown on the picture