After the introduction of Islam in the seventh century, gambling became strongly forbidden by religious law . Gambling was a problematic issue, with potential detriment to the individual and society.
Throughout Iranian history, the legality of gambling depended on the current regime in power.
Before the 1979 Islamic Iranian revolution, gambling was permitted, and the Shah (or king) owned four out of the eight casinos in the country. With the enforcement of Sharia Law in post-revolution Iran, however, gambling became strictly prohibited, and the casinos were closed.
CHIPGUIDE says “In 1979, Ayatollah Khomeini shut down all 57 casinos in Iran. They were owned by the Shah Mohammad Reza Pahlavi Foundation.”
Not too much??? I could only found a few. And not all owned by Pahlavi Foundation. Some were privately owned.
According to the documents below the casino owned by Mr. Rahim Ali Khorram should worked in the period 1976-1979.
1-A telegram sent by American Embassy on 1976 July, 26 ( reproduced from wikileaks)
https://www.wikileaks.org/plusd/cables/1976TEHRAN07574_b.html

PERMISSION TO OPERATE GAMBLING CASINOS IN IRAN CAN BE GRANTED ONLY BY THE HIGHEST AUTHORITY. SUCH ESTABLISHMENTS TECHNICALLY ARE ILLEGAL.
THE PAHLAVI FONDATION REPORTEDLY HAS A CONTROLLING INTEREST IN CASINOS AT RAMSAR AND NAMAKABRUD, ON THE CASPIAN, AND AT ABELI. THESE FALL UNDER THE JURISDICTION OF SENATOR ZIAI, PRESIDENT, IRAN CHAMBER OF COMMERCE, INDUSTRY AND MINES, TEHRAN.
IN ADDITION, THE PRIVATELY OWNED VARIAN CASINO OPERATES AT KARAJ, A SUBURB OF TEHRAN MANAGING DIRECTOR IS MR. AHMAD GHASEBII, 31 AFSHIN STREET, SHAH ABBAS AVENUE, TEHRAN.
IT IS RUMORED THAT ANOTHER PRIVATE CLUB(CASINO) WITH FRENCH INTERESTS IN COOPERATION WITH A MR. KHORRAM WILL SOON OPEN WEST OF TEHRAN; HOWEVER, NO ADDITIONAL INFORMATION IS AVAILABLE TO THE EMBASSY, REGARDING THE PARTICIPANTS, INCLUDING THE ADDRESS OF MR. KHORRAM.

After 1979 the Islamic Republic’s authorities have executed individuals who were convicted by Revolutionary Tribunals, on charges such as drug trafficking, sexual, and other criminal offences ( gambling
i.e)
2-From "NEW YORK TIMES May 10, 1979"
“The second multimillionaire to be executed at 1 A.M. today after trials that began yesterday was Rahim Ali Khorram, who though illiterate rose to a position of power and influence, with vast property holdings, an asphalt company, hotel and a huge amusement park bearing his name.
Witnesses testified that the amusement park also contained a secret morgue and a cemetery in which Mr. Khorram hid the bodies of many enemies. One witness said that he also once had a man thrown into the cage of the park's lion, resulting in the man's death.
Mr. Khorram was also accused of operating gambling casinos and maintaining more than 100 Filipino pros...ti.. tu.. tes. Among their regular clientele, it was charged, the former head of Savak's security police. Mr. Khorram was described by the court as a “first‐class corrupt on the earth”
Hope this information is useful.
NICE PLAQUES TORREY. CONGRATULATIONS.