Title: Operation Longlife
Description: From the back cover:

FOOLS' GOAL

In the twenty-first century, Avery Jarvis "Doc" Brandon lived in luxurious seclusion on subtropical Nameless Island.  An immensely wealthy gene-engineer who dabbled in illegal baby-making.  Doc was 186 years of age and looked thirty-five.

But a storm loomed on his horizon: Bureaucrats had blundered across Doc's real age.  They wanted his "secret discovery" and would undertake anything -- including blackmail, kidnapping and murder -- to get it.
Subjects: American Science fiction