I wouldn't think that there is the slightest chance of obtaining a "most accurate" rifle by making a choice based on model or manufacturer. There is no statistical evidence at all that supports any sort of correlation, let alone the data set and laboratory research that might be needed to even detect variations due to metallurgy or machining patterns.
Shooting performance of the rifle is purely down to bore condition and bedding. Again, there is no evidence that any of the well-known gunsmiths were doing anything to a No4 other than selecting a decent barrel and making sure the forend was a good fit. If there was a "secret formula", presumably we'd by now all know that "X's SRb model can reliably shoot 1/4 moa" etc. On the contrary, if you look at dozens of Fultons SRb No4s, they are a complete bag of bitsas - many are made from mixed manufacturer parts.