Woody,
There is no problem in pointing out what could be a mistake. It's been a few years since I accumulated that information and I am out of town until late Sunday. I'll look up the numbers in several manuals and post them late Sunday. The high pressure 235/261 numbers most likely came from a 1954 manual.
As stated above, the settings came from, "various Shop Manuals and Owners Manuals (they do not always agree, even in the same year)".
That 1955 Shop Manual that you linked shows a setting of .020 for the intake valves. That seems very wide.
Take a look at the same year's Owner's Manual: .006" for intake (and .016" for exhaust).
Tim
