There are no guarantees for big-screen immortality. Consider the case of Tisa Farrow. She is a beautiful woman--fair, blue-eyed, and bountiful of God-given bust. Her father was movie director John Farrow. Mom Maureen O'Sullivan had been a flashy, hot-bodied movie star swinging through the trees in a skimpy animal-hide one-piece with Tarzan. And still Tisa, unlike her phenomenally famous sister Mia Farrow will pass from this life having been relatively obscure. A film actress by vocation, Tisa plied her trade in a string of European-made exploito pictures and a few lesser-known American titles. About all that is remembered from her movie career are the topless shots in Some Call It Loving (1973) and a profile of boob in shadow with extended nipple in L'Ultimo cacciatore (1980). Wait a second, maybe there is one guarantee for big-screen immortality after all.