Following Y.Y.'s request, I spent a few minutes and printed out the problematic Taz posted last week (The space left was too small to fit 9 yudin b'tziruf). I amended it with a pencil to show how I would add ink to certain letters to create a space of 9 yudin btziruf (combined). It would thus be kosher after repair.
A few points:
1) It was a bit clumsy doing it with pencil (a rapidograph would have been easier but the ink bled as soon as it came in contact with the paper I was using (hence the mechikah by the taf).
2) At no point during the repair was there a shinuy tzurah or panim chadashos. (it meant thickening the vavs from the bottom up, and doing some letters, such as the taf in stages, ensuring that at least a fraction of the bottom left regel remained exposed.
3) Frankly, before attempting such a tikkun it would be wise to photocopy the parsha and plan the tikun by sketching it in with pencil first. Once you are satisfied with the result you can use the sketch as a template. It will make it a far less nerve wracking exercise!