Dangerous, as in makes holes in the pistons in less than 1 minute.
The mechanical advance is never enough for maximum mileage. Depending on temp and mix, over 50° total with vacuum may be useful - but it has to vanish almost instantly with falling vacuum.
The throttle blade angle is more likely to be a problem with a cam bigger than about 240° @ .050". The symptom is typically that if you have to increase idle speed to prevent a stall due to roughness at 7-800 RPM, then you get a flat spot (perhaps a pop) above idle. If you have neither, don't worry about it.
