You don't need to release your first map just to port models. Porting 10 cod4 models takes 2 minutes, and about 5 black ops models take around 10 (converting images takes time), and a black ops gun takes around 10 minutes too. Some people, like Quizz, have made multiple, revamped versions of their map, like last stand elite. You could to the same. You could make another version with cod4 models, cod4 guns, terrain patches, alpha blending, etc once you are familiar with the tools.