OK now I got pair of extra eyes and hands to check the carb. When pedal was floored, the throttles opened only 3/4, not fully open. The throttle linkage just wasn´t correctly adjusted. In purpose, to save dynaflow and fuel, I don´t know.
Now throttles open fully and last half inch of the movement also moves the linkage to transmission. I went for a test drive, the effect wasn´t dramatic but of course there´s more power at full throttle. And yes, I´m gonna be careful and not to destroy the 50+ years old fine running machine, I absolutely enjoy more smooth and slow ride. I think I´m gonna keep this carburetor because it works ok for me.
We also replaced front break reaction rod bushings and motor mounts yesterday, and I can tell that the effect was huge. Now when the swing arm doesn´t move front and back anymore, the car isn´t wiggling all over when braking hard. Also there´s much less vibration because of the new motor mounts.
Thanks again everyone for your great comments and advice.