To be clear, the longer life of vegans is not due to having more nutrients. It is due to having a specific nutrient deficiency. That also BTW has other effects that aren't clearly desirable.

Energy restriction (calorie restriction) has the biggest longevity effect. But nobody wants to live like that. You are always cold, have no energy to do anything, have no sex drive, and you live basically in this "statis" mode, waiting for better times.

IMHO lifespan is not the only important variable, and a high meat diet with low-carb vegetables is IMHO a great option.