RE: How fast?
Oh, forgot to mention. When I clocked my Atlanta I did this. Go to Google Earth and display your field. I found two prominent landmarks (trees, etc) and measured the distance with their ruler tool. I then flew through them with a stopwatch. If you know distance traveled and you know trip time you can easily work out speed. That''s how many speed trials for real racing aircraft were often done back in the golden age.
P.S. I came up with a speed of 138 mph coming out of a shallow dive with the engine full screaming open turning a 12x12 APC. [8D]