Seems to me that my experience with those high flow thermostats - Robert Shaw type in particular from Mr. Gasket - was that the 160º version worked fine (with the drilled ports added). But........... when I tried the same thing in a 180º version it was poor quality and failed. Back to the 160º and things worked OK, but I was hoping to get the warmer running temp for cooler weather. I think Charlie had a similar experience - the 180º version just wasn't a reliable part.
My engine with the mods you were talking about - bypass orifice, small pulley, more fan blades and so forth - seems to want to run about 100º over ambient (small T-bird radiator and the goofy 1" spacer behind the water pump). Rather than going all the way down to a 160º water temp in winter - the 180º would be preferable.
Steve Metzger Tucson, Arizona