I beleive you might be on to something, Denny. After all, these old carbs were not designed with what passes for "gasoline" thse days. I will add that my suggestion on the timing was based on personal experience with a similar problem. With a stock engine/oe type distributor, I would only suggest no more than 5 degrees advance, which well within the range of the "octane selector" on the vacuum advance. I had to go 15 degrees on mine, but my enging is not stock, and the distributor I'm running doesn't have a vacuum advance. I also have never run Rochester on mine, only Carter YF and, currently, Holley 1904.
