May an Ashkenaz minyan use a sephardic torah (written in כתב וועליש) for their minyan or vise versa? Please cite a source
Taken from my answer here:
Yalkut Yosef 685:12
ומתוך ספר תורה בכתב אשכנזי, יצאו ידי חובה
וכן ההיפך, שהכל יוצאים ידי חובה בספר תורה שנכתב בכתב ספרדי, אף שהיו''ד של הצד''י נכתב כיו''ד הפוכה.
a) A Sefaradi who heard from a Ahkenazi written Sefer Torah is Yose.
b) An Ashkenazi is also Yose from a Torah written in Sefaradi style.
One can infer from the fact the he does not mention the "petzua daka" issue, that it would not be a problem (although he doesn't seem to say so explicitly).
Therefore, I don't think it's an issue.
Just to throw in a few more modern sources: Har Tzevi OC 1:32, Minchat Yitzchak 4:47 and Mishneh Halachot 7:8 all explicitly rule that Vellish is kosher. Tzitz Eliezer 14:3:4 permits post facto even Sta"m that was written with a mix of Vellish and Ashkenazi. Igrot Moshe OC 5:2 also permits other forms of writing but he is quick to point out that it is better to stick to one's custom on the matter.