Horrible idea... He can play in a "3 big" lineup but he wont be a small forward.
Small Forwards in NBA: Hedo Turkoglu, Josh Howard, Paul Pierce, Gerald Wallace, Andre Iguodala, Richard Jefferson, Rudy Gay, etc
Blake is not that kind of player... He is a prototype power forward, and he can use his perimeter skills (such as ball handling) to his advantage against other power forwards and centers.
Never gonna happen....