Garth Drabinsky ended speculation last week about plans for his much-praised , all-star revival of “Show Boat.” He’s bringing the production, staged by Harold Prince, to Broadway’s Gershwin Theater in September, with an opening slated for Oct. 2.Drabinsky also said that the costs of mounting and running the show will almost certainly result in a new Broadway top ticket price, possibly as high as $ 75. The current top, $ 65, has been in effect since the spring of 1992. The top price for the show in Toronto is $ C85 ($ 64). “The reality is, we are going to have to raise ticket prices,” the producer said, adding that the Broadway top probably would not exceed $ 75. In the past, when one Broadway producer set a new top ticket price, others quickly followed suit. The Live Entertainment of Canada (Livent) production, whichopened Oct. 17 at the North York Performing Arts Center in northern Toronto and currently has an advance of $ 7.5 million, stars Robert Morse, Elaine Stritch, Rebecca Luker, Lonette McKee and Mark Jacoby. Prince, following fast on the heels of his Drabinsky-produced “Kiss of the Spider Woman,” directed the show, with choreography by Susan Stroman of “Crazy for You.” The revival won nearly universal critical acclaim as a revisionist rendering of the 1927 Jerome Kern classic that respected the lush vitality of one of Broadway’s most revered scores while accenting the story’s serious themes. The production also inspired protests from a coalition that labeled the show racist. Drabinsky’s plan from the beginning has been to bring the show into the Gershwin — at 1,924 seats, Broadway’s largest theater — to accommodate a physical production that includes 71 actors and an orchestra of 30. Positive reviews for the show increased the pressure on “The Red Shoes,” the $ 8 million Martin Starger production that was about to begin its troubled tryout run at the theater. When that show flopped instantly, speculation began that Drabinsky would bring “Show Boat” in by early spring, loading up a season already heavy with revivals. “I would have loved coming in with all the flurry of excitement the show has generated,” Drabinsky admitted. “It was a tough decision, but I needed time to market the show properly, and I don’t mind addressing the imbalance of shows opening in the fall and spring.” That position was shared by Prince, who pushed for a fall opening. As a result, Drabinsky will be paying rent on the Gershwin to the Nederlander Organization to hold the house until September. He declined to say how much that cost would add to the capitalization. The Broadway production will cost about the same as the one in Toronto –$ 7. 5 million — Drabinsky said, adding that the Eugene Lee set and Florence Klotz costumes would be constructed in Canada. But the running costs will be considerably higher because of differences in union wages. But with about 1,600 of the Gershwin’s 1,924 seats possibly going at the top price, “Show Boat” could have a weekly gross potential in excess of $ 900,000. The original production of “Show Boat” was mounted on Broadway by Florenz Ziegfeld at his namesake theater, with a top ticket of $ 5.50. While “Show Boat” is by no means a guaranteed hit in New York — an acclaimed Houston Grand Opera revival had only a brief run 10 years ago at the Gershwin — its success in Toronto finds Drabinsky on a roll. Despite reviews that ran the gamut from acclaim to disdain, “Kiss” has played well on Broadway and should recoup by late spring. The former Cineplex Odeon topper said that “Show Boat” will be financed solely by Livent, as will a national touring company in the spring of 1995.