LOUISVILLE, KY. — It seems every mass marketer at one time or another talks about how far its product would go end-to-end. The latest is Kentucky Fried Chicken. The company says its worldwide sales last year of chicken, if laid head to claw, would stretch from the earth to the moon and 42,000 miles beyond. The chain served the equivalent of more than half a billion chickens. Total sales reached $5.4 billion.