Despite costs of integrating its recent acquisitions and the impact of the ongoing strikes against GM, Lear Corp. reports an 8% increase in its second-quarter earnings to $65.7 million from $61.1 million a year ago. On a per-share basis, Lear earned 96 cents for the quarter ended June 27. Excluding the effect of the GM strikes, Lear officials estimate the company would have earned $1.10 per share, or $75.3 million. Total sales rose 18% to $2.2 billion from $1.8 billion, primarily reflecting recent acquisitions. Of that sales increase, 70% of it came from operations outside the U.S. and Canada. To put the performance in perspective with the rest of the industry, Lear's second-quarter return on sales was 3%, down from 3.3% a year earlier. That compares with Ford Motor Co.'s 6.6% return on sales for the same period, Chrysler Corp.'s 5.9% and GM's 1.2%. Separately, Lear signs an agreement with the Portuguese government under which it will establish an automotive seat trim manufacturing plant near Lisbon that could employ about 4,000 by the year 2000.