Would u breed a separate line or introduce themm into your current line.
If you have two dogs outside of your "line" that you are that impressed with, I would first question the "line".
Only time I would breed outside of my own line would be for a hybrid vigor (health) outcross. Its my personal opinion that if your outcrossing a line for reasons of improvement, then you started with the wrong dogs.
If you don't have a "line" of dogs your breeding, then I wouldn't hesitate breeding two outstanding unknowns. I would however expect there to be great diversity within the litter and would plan on keeping them all to sort through and see if I could find what I was looking for. That's basically how all lines are begun.