Question: What type of a scholar was the rabbi who asked Rabbi Dovid Povarsky to join the previous two heads of the institute?

Context paragraphs:
Akiva Grunblatt: Akiva Grunblatt is an Orthodox rabbi who as co-rosh yeshiva (dean) heads the Yeshivas Rabbeinu Yisrael Meir HaKohen.  (Yeshivas Chofetz Chaim) in Flushing, New York.  (The other co-rosh yeshiva is Rabbi Dovid Harris.)  Before being appointed to his current position in 2000, he was a rosh yeshiva at Yeshiva Toras Chaim in Miami, Florida.

Talmudical Institute of Upstate New York: The Talmudical Institute of Upstate New York (TIUNY) is an all male educational institution for high school and college age young men located in Rochester, New York.  It is primarily an American, Lithuanian style Haredi but non-Hasidic yeshiva.  TIUNY was founded in 1974 as the first external affiliate branch of the education network by Rabbi Menachem Davidowitz and Rabbi Dovid Harris.

Chanoch Henoch Bornsztain: Chanoch Henoch Bornsztain (died 23 September 1965), also spelled Borenstein or Bernstein, was the fourth Rebbe of the Sochatchov Hasidic dynasty.  He acceded to the position of Rebbe following the death of his older brother, Rabbi Dovid Bornsztain, the third Sochatchover Rebbe, who died in the Warsaw Ghetto during the Holocaust.  Rabbi Dovid's children were also killed during the Holocaust, leaving no survivors.  As Rabbi Chanoch Henoch had moved to Mandatory Palestine and established a beth midrash in Jerusalem during the 1920s, his assumption of the title of Admor relocated the Sochatchover dynasty from its home in Poland to the new state of Israel, where it flourishes to this day.

Valley Torah High School: Valley Torah High School is an Orthodox Jewish high school located in Valley Village, California, a northern suburb of Los Angeles.  The school has two separate divisions: a Boys Division, and a Girls Division.  The current Dean and Rosh Yeshiva is Rabbi Avraham Stulburger.  The Boys Division Principal is Rabbi Dovid Felt and their General Studies Principal is Dr. Eliezer Jones.  The Girls Division Principal is Mrs. Sheindy Gross and their The General Studies Principal is Mr. Randy Rutschman.

Dovid Shlomo Novoseller: Rabbi Dovid Shlomo Novoseller, a descendant of Rabbi Levi Yitzchok of Berditchev (Kedushat Levi), Rabbi Samuel Eidels (Maharsha) and Rabbi Yechezkel Landau (Noda Biyehuda), was born in Yarmolintsky on Aug. 19, 1877, and received semicha from Rabbi Moshe Noson HaLevi Rubinstein, Av Beth Din of Vinnitsa.

Dovid Povarsky: Rabbi Dovid Povarsky (Hebrew: יהושע דוד פוברסקי‎ "Yehoshua Dovid Povarsky"; 1902–1999) is known for his erudite Talmudic lectures and his deanship as Rosh Yeshiva of Ponevezh Yeshiva.  He was asked by Rabbi Yosef Shlomo Kahaneman to join the previous two heads of the institute, Rabbi Elazar Menachem Shach and Rabbi Shmuel Rozovsky to create a triumvirate in leading the Yeshiva.

Hillel Fendel: Hillel Fendel (Hebrew: הלל פנדל‎ ‎ ) was, for 16 years, senior editor and co-founder of Arutz Sheva's "Israel National News" and also works as an author and editor.  He worked as a teacher and rabbi in the past.  He is a son of Rabbi Meyer Fendel, founder of Hebrew Academy of Nassau County, and the brother of Rabbi Dovid Fendel, founder of the Hesder Yeshiva of Sderot.  He is also a nephew of the late Orthodox Jewish educator and author, Rabbi Zechariah Fendel.

Yosef Shlomo Kahaneman: Yosef Shlomo Kahaneman (1886–1969), , was an Orthodox rabbi and rosh yeshiva of the Ponevezh Yeshiva.  He was a renowned Torah and Talmudic scholar, a distinguished member of the Council of Torah Sages of Agudath Israel.

Yisroel Neuman: Yisroel Tzvi Neuman (born April 1947) is an Orthodox rabbi and one of the four roshei yeshiva (deans) of Beth Medrash Govoha (the Lakewood Yeshiva) in Lakewood, New Jersey.  He shares this post with Rabbi Malkiel Kotler, Rabbi Yerucham Olshin, and Rabbi Dovid Schustal.  He is married to the daughter of Rav Dov Schwartzman, who is a granddaughter of the founder of the yeshiva, Rabbi Aharon Kotler.

Elazar Shach: Elazar Menachem Man Shach (Hebrew: אלעזר מנחם מן שך‎ ) Elazar Shach (January 1, 1899 O.S. – November 2, 2001) was a leading Lithuanian-Jewish Haredi rabbi in Bnei Brak, Israel.  He also served as one of three co-deans of the Ponevezh Yeshiva in Bnei Brak, along with Rabbis Shmuel Rozovsky and Dovid Povarsky.

Supporting paragraphs: Dovid Povarsky Yosef Shlomo Kahaneman
Answer: Torah and Talmudic scholar