The Ampex Corp unit of Allied-Signal Inc has been on the block since shortly after Allied merged with Signal, and a buyer has finally been found for the diversified electronics business. The Redwood, California company is going to privately held New York chemical products manufacturer Lanesborough Corp for $479m. Ampex makes a variety of disk and tape products, displays, add-in memory and processor boards, and had 1986 sales of more than $500m.