If you trashed a steel fork to the point where its unusable, you hit something really hard. I would check the frame for kinks or bulges on the top and down tubes near the head-tube.
As far as the legnth goes, the best fix is to cut the steerer tube to the right size, and depending on how much of the steerer is threaded, you may have to cut some additional threads.
Il faut de l'audace, encore de l'audace, toujours de l'audace
1980 3Rensho-- 1975 Raleigh Sprite 3spd
1990s Raleigh M20 MTB--2007 Windsor Hour (track)
1988 Ducati 750 F1