How to quickly change all selected notes into fixed pitch?

How to quickly change all selected notes into a fixed pitch? (as shown in the picture below)

Hi! If you have some keyboard shortcut to change to downstem voice, you could use it, then l (lock duration), a space a space a space… Select those bars, filter downstem voice (I also have a shortcut for that), change to upstem voice 1 (another shortcut). Really faster done than explained. Or you could simply use l and rewrite the pitches (with a MIDI keyboard it could be very fast). I’m sure there are other workflows possible. But none is in one or two steps, I think.