Can a 1997 Chevy suburban with grill and headlight assembly sealed beam style be replaced composite grill?

No, a 1997 Chevy Suburban with sealed beam headlights cannot directly accept a composite grill designed for models with separate headlight housings (like the later, more modern composite headlight assemblies). The sealed beam units are a completely different shape and size and integrate with the grille in a different way. You'd need a grille specifically designed for a 1997 Suburban with sealed beam headlights. Trying to force a composite grille meant for a different headlight setup would be impossible and likely damage both the grille and the Suburban's front end.