typically the drive side spokes are 1+mm SHORTER for a 5 speed, 120mm OLD wheel
and 2mm Shorter on a 125-126mm 6-7 speed hub.
the Optimal length is where the spoke fills the nipple all the way or nearly all the way, beyond the slot, not beyond the end.
Way back a shop would have a grinding wheel and grind them back.
Correct practice is select the correct length spokes.
Grinding back reduces the adjustment for truing the wheel later.
On a wheel like this, any serious truing should have the tire and rim strip off the wheel to monitor and correct (grind, file) if needed.
Easier to monitor roundness too.