[Arran]

I can't speak for this particular model but one area where they had some leeway was in the plate load resistor on the 1st audio tube, it could be 470K, or 500K, or 250K or 270K Ohms, and all will work with little to no difference in performance as plate voltage is less critical then either cathode or grid voltage. The usual production variants that Philco engaged in, unless it was a needed design modification (lots of those in early TVs) was in swapping tubes, particularly from Octal to Loctal, or back again. For some reason a lot of their early 40s models went "retro" on the tube types, they started using things like #84s, and #41s, #42s, even though they had used "G" style octals in 1937-38, it's really funny seeing a set with loctal types, with a pair of #41s as power outputs, and also a 6A8G. This is why you need to confirm the Code number, and production run of your chassis, or it can be very confusing working with the wrong diagram. When Canadian RCA, or CGE made changes they changed the model number by adding a suffix like "A" after the model number, Canadian Philcos were even worse in that liked to do their own thing, and used their own model numbers, usually two digit ones like "Model 76" which has no relation to the early 30s model at all. One thing that I will say about the Toronto Philco sets is that they usually stuck to the same schematic through the life of the model year.
Regards
Arran