Controlling stem lengths in a global way

[Knute Snortum]

I am engraving a piece where there are many groups of 16th notes where
the first note is normal size and the rest should look like grace
notes.  I'm using \scaledDurations, \magnifyMusic and \normalsize to
do this, but I'm running into a systemic problem: the stems of the
normal size notes are mostly too short (they'd be fine if they were
grace notes).  To get around this I'm using beam position overrides
and tweaks, but this gets tedious quickly.  Is there a) a systemic way
to tweak the stem lengths, and/or b) better way for me to do this?

%%%
\version "2.22.2"
\language "english"

ns = \once \normalsize

% Short stems on the normalsize notes
\relative d'' {
  \magnifyMusic #2/3 {
    \scaleDurations 2/3 {
      \ns d16 f, g c, f g  \ns c e, g c, e g
      \ns c d, g c, d g  \ns c e, g c, e g |
    }
  }
}

beamPositionA = \tweak Beam.positions #'(4 . 2) \etc
beamPositionB = \override Beam.positions = #'(3 . 1)

% Need to tweak or override many, many notes
\relative d'' {
  \magnifyMusic #2/3 {
    \scaleDurations 2/3 {
      \ns \beamPositionA d16 f, g c, f g  \ns \beamPositionB c e, g c, e g
      \ns c d, g c, d g  \ns c e, g c, e g \revert Beam.positions |
    }
  }
}
%%%

--
Knute Snortum