American Broadcasting Companies Inc. and Capital Cities Communications Inc. revealed plans yesterday to sell valuable media properties in major cities throughout the nation as part of their previously announced $3.5 billion merger.

The companies said in a joint proxy statement mailed to shareholders that they would ask the Federal Communications Commission to waive a rule that would prohibit them from owning WPVI-TV in Philadelphia and WABC-TV in New York because the stations' signals overlap.

If that request is denied, they will sell WPVI, along with three other television stations, 15 radio stations, all of Capital Cities' cable television operations and The Red Bank Register Co., a New Jersey newspaper company, to meet FCC restrictions on multiple ownership of media properties. "This is the largest block of stations for sale at one time I've ever seen," said FCC Commissioner James H. Quello.

In the biggest recent media sale agreement, Metromedia Inc. said it would sell seven television stations to Australian publisher Rupert Murdoch and Denver oilman Marvin Davis for about $2 billion.

Goldman, Sachs & Co., which will handle the transaction, is expected to solicit bids from a pre-approved list of potential buyers.

Quello said Capital Cities will have to formally present its case for a waiver, which he indicated he favored. "Their Philadelphia waiver request is a reasonable one because the overlap between New York and Philadelphia is more technical than practical. They are two very separate markets. I'm only one vote, but they should have a good chance of making it," Quello said.

The proxy statement said the following television properties will be sold if the FCC waiver is granted: Capital Cities television station WTNH-TV, New Haven; WFTS-TV, Tampa; WKBW-TV Buffalo; and ABC television station WXYZ-TV, Detroit. If the FCC waiver is not granted, then WPVI-TV in Philadelphia will be sold and WXYZ-TV in Detroit will be retained.

Capital Cities cable television operations will be sold to meet a FCC rule that prohibits a television network from owning cable properties. Capital Cities has interests in 55 cable television systems serving 372,790 basic subscribers, according to the proxy statement.

The proxy statement said the following radio stations will be sold: Capital Cities radio properties WPAT (AM and FM), Paterson, N.J.; KLAC-AM and KZLA-FM, Los Angeles; WKBW-AM, Buffalo; and ABC radio stations KTKS-FM, Dallas; KSRR-FM, Houston; WRIF-FM, Detroit; WABC-AM and WPLJ-FM, New York City; KLABC-AM and KLOS-FM, Los Angeles; WLS (AM and FM), Chicago; and KGO-AM, San Francisco.

It is difficult to predict accurately how much the sale of the properties will bring, but some industry estimates exceed $1 billion. In several recent media deals, buyers have been willing to pay prices well above such estimates.

The proxy statement, which provides details of the merger agreement in which Capital Cities will acquire ABC in the first change of control of a major television network, said both companies will have annual meetings on June 25 for shareholders to vote on the agreement. Shareholders of both companies are expected to ratify the deal.

ABC stockholders would receive $118 in cash and one-tenth of a warrant (right) to purchase one share of Capital Cities stock at $250 a share for each of their shares. First Boston Corp. has told ABC directors that it believes the price is fair. ABC has agreed to pay First Boston a $7.5 million fee for serving as its financial adviser in the merger.

The proxy statement said Berkshire Hathaway, a company controlled by Omaha investor Warren Buffett, will buy 19 percent of Capital Cities for $517.5 million, or $172.50 a share, as part of the deal. Those funds will be used by Capital Cities to help finance the merger.

As part of the agreement, Berkshire Hathaway has agreed that it will allow Capital Cities Chairman Thomas F. Murphy to have voting control of its shares for 11 years, and that it will not increase its stake in the company to more than 30 percent without Capital Cities' approval. The New York Stock Exchange has advised Capital Cities informally that this agreement violate NYSE's rules and may cause it to delist the company's common stock from the Big Board, the proxy statement said.

The proxy statement said the board of directors of Capital Cities/ABC Inc. would include Leonard H. Goldenson, the current chairman and chief executive officer of ABC, and Frederick S. Pierce, the current president of ABC. Pierce also would become chairman and chief executive officer of ABC following the merger. Capital Cities Chairman Murphy will continue to serve as chairman and Capital Cities President Daniel B. Burke will continue to serve as president of the parent company. Capital Cities also plans to elect Buffett or a designated representative of Berkshire Hathaway to its board.

The proxy statement said the companies intend to complete the merger sometime after Jan. 1, 1986, following necesary approval by shareholders, the FCC and other government agencies. While Capital Cities has not yet obtained firm commitments for the borrowings it needs to acquire ABC, that is not expected to be an obstacle to the merger.

The combination would create a media giant with major television stations, newspapers and magazines that would have had combined revenues of $4.4 billion and net income of $133 million at Dec. 31, 1984.