I can't imagine there being a nicer 58 Laurentian sedan out there anywhere.

My research as documented in the thread about engine colours and names which resides in the Library shows that the the tri-5 years got green V8's as well as green 261's. 1958 was the first year for orange V8's in Canadian Pontiacs. The six remained green until replaced in 1963 by the 230 which was also orange. This is not the first time I have heard of green small blocks in '58's so perhaps there was a transition period. I will defer to my esteemed friend George however as he is the expert in this era. The ad does indicate that this is a two owner car and is numbers matching and also sales brochure does not show green V8 engines.