Short mast means you'll have major issues with the boom hitting you as it comes across the boat. You need to repair or replace it.
That is why racers have adjustable goosenecks - the draft moves as the wind picks up, and the C/E moves. If the gooseneck is too far fwd, the C/E is too far back and you get weather helm, and if the C/E is too far fwd you get lee helm. The one foot mast difference makes little difference and could be compensated for by moving the gooseneck back if needed. The short mast is the same as having a Jens rig in all the time, which is not a bad thing for recreational sailing (Jens is too complicated for rec sailing, but having an automatic Jens is as with a short mast is simple and helps depower a bit when it is windy.)Assuming the height of the lower spar is maintained constant, varying the length of the mast moves the entire sail forward for a longer mast and aft for a shorter one. I doubt a one foot difference makes much, if any difference, but I'm curious as to how the sailing qualities would change if the sail were moved more significantly fore or aft.
Could it be said the jens rig depowers MAINLY bevause you're decreasing tbe overall sail height,
He's got about one foot of old mast material--now!If you're good, get some old mast material, and make an internal compression sleeve + missing mast section. It will never break again!