Two 14" hearts will give you around 96. So if you take away the points to shape the body, that will still cover your 80 servings plus the boobs. But I would probably do double 12" hearts (68 servings minus the points) plus the boobs ( I think 12 per boob if you use the wonder mold).
When I first started doing cakes 30 years ago, this type of cake was all the rage for birthdays and bachelor parties. I used 11x15 or 12x18 sheets, then carved out the waistline. We used two ball-pan cakes for the boobs. (Yeah....she DID look like a 48DDD!)
A 2-layer 11x15 serves 70 and a 2-layer 12x18 serves 108 BEFORE carving and not counting the boobs.