Best Products Co. Inc., one of the nation's largest discount retailers, reported that its net income for the fourth quarter ending Feb. 2 decreased 29 percent to $22.3 million (83 cents a share) on sales of $915.8 million.

That compared with restated net income of $31.3 million ($1.15) on sales of $844.9 million during the same period in 1983.

For the year, the Richmond-based company said its earnings were $13.6 million (50 cents) last year, down from a restated $33 million ($1.25) for 1983.

Sales for the year rose 8.2 percent to $2.25 billion, compared with $2.08 billion for 1983.

"Even though sales were at a record high, this result does not offset the costs of organization changes we are making at every level," said Best President Robert E. R. Huntley.

Huntley said that last year marked the turning point in the company's assimilation of Modern Merchandising and Basco, the catalog showroom chains it had acquired in 1982.

"We are now moving aggressively to take advantage of our new size, but these changes entail significant costs in the near term," he said.

Best's 1983 earnings have been restated to reflect a change in the company's method of accounting.

The Stanwick Corp., an Arlington firm that provides maintenance management, integrated logistic support, systems engineering and management and technical support to private industries and the government, reported that its earnings for the third quarter ending Jan. 31 dropped to $3,592, compared with $1.8 million ($1.76) during the same period last year.

Revenue for the third quarter dropped slightly to $1 million, compared with $1.24 million during the same period last year.

For the nine months, net income dropped to $199,754 (20 cents) on revenue of $3.7 million, compared with $1.8 million ($1.44) on revenue of $3.6 million during the same period last year.

The company attributed its third-quarter earnings to higher net interest income, a premium refund due to the termination of an insurance policy and the elimination of excess reserves following payment of a state tax assessment.

Potomac Electric Power Co. reported earnings of $26 million (50 cents) for the two months ended Feb. 28, compared with $25.8 million (49 cents) during the same period last year.

For the year, Pepco said its net income was $168 million ($3.24), compared with $149 million ($2.85) during the same period a year earlier.