Northwest Industries Inc., the Chicago-based conglomerate that makes everything from Fruit of the Loom brand products to industrial batteries, said today it has agreed to be acquired for about $1.4 billion by Chicago financier William Farley, a minority owner of the Chicago White Sox.

Northwest has been looking for a buyer since ending its agreement to be acquired in late January by Kelly, Briggs & Associates, after an investor group led by former Esmark Inc. Chairman Donald P. Kelly failed to obtain financing.

Wall Street sources said today Farley plans to finance his acquisition of Northwest through a combination of bank loans and $500 million raised through the sale of high-yield "junk" bonds by his financial adviser, Drexel Burnham Lambert Inc.

Junk bonds, securities frequently issued to finance takeovers, are riskier than rated bonds and therefore pay a higher rate of interest.

Northwest said that its stockholders would receive $42.50 in cash, $7.50 face value in a new 13.5 percent exchangeable preferred stock, and one share of Lone Star Steel Co. for each Northwest share. Lone Star Steel is a Northwest subsidiary that will be spun off as an independent, public company.

As a result of the deal, Northwest is postponing its May 14 stockholders meeting until sometime this summer, and the company expects the deal to be completed by Labor Day. Northwest stock closed today at 55 7/8, down 1.

There has been widespread speculation recently that Farley, a former encyclopedia salesman who has built a financial empire by acquiring a variety of businesses in the last eight years with borrowed money, was lining up $1 billion for a possible Northwest bid. Unlike some dealmakers who move in and out of companies for a quick profit, Farley has kept most of his acquisitions. His reputation is based on his ability to boost the performance of the companies he acquires.

Northwest Chairman Ben W. Heineman, nearing retirement, has been searching for a way to maximize the value of the company's stock for shareholders. He hired both Salomon Brothers and Goldman, Sachs & Co. to explore Northwest's alternatives, which led to the deal with Farley.

Northwest subsidiaries include Union Underwear Co., a profitable concern that makes Fruit of the Loom brand products; Velsicol Chemical Corp., a troubled agricultural chemical subsidiary; Acme Boot Co., the world's largest manufacturer of cowboy boots; General Battery Corp., an industrial and automotive battery maker; NWT Natural Resources, an oil and gas exploration company; Lone Star Steel, a leading producer of oil service products that will be spun off as a public company; and Universal Manufacturing Corp., a manufacturer of small transformers used in lighting fixtures.

Northwest also owns 4.8 million shares of Pogo Producing Co., worth about $84 million at current stock prices.