Tims sermon pretty well covers it [for pre-55 anyway

], but I'll add more worms to the can - I've studied
these 1959 assembly line photos a number of times, which appear to show 2 different shades of gray on 6 cylinder engines and only the 'common' orange on all the V8s, whereas Hensels list shows the 59 passenger car 6's as blue, truck V8s as gray or green, and 261 as green - the plant pictured [Tarrytown] appears to have had 3 lines to assemble cars and 1 for trucks, surely among the trucks assembled during the photo-shoot period there would have been a few trucks getting the optional V8 or 261 .... note also it looks like the engines are first shown in a 'receiving' area, offloaded from train cars - how many engine producing plants were there? did they all [if more than 1] source paint from the same supplier? would GM have bothered changing the engine color formulas purposely at particular times, or were year variations dependent on the vagaries of suppliers, and "just in time" dictates? we'll never know, it's not called out in the assembly manuals .... and to the OPs question,
what was the situation for Canadian production?
Denny has come close to matching one particular truck as he found it, from one particular year, from one particular plant, 50+ years later .... was that engine produced the same year as the truck? did that plant get engines from the same engine plant as other assembly plants? was all the engine paint
that year produced at the same time in the same place? how does it relate to other years? no documentation = nobody knows what color a particular year engine was/is/"should" be
Bill