re: Smoking Baby Back Ribs

If they came out tough with the 321 method, like you know, the temp was too high or you cooked too long.
Some baby backs have a lot less meat compared to other baby backs. You will always have to adjust. I usually adjust temperature instead of time, because I have a controlled electric smoker. On a pit, I suggest shooting for a lower temp. If still having trouble, try placing foil/pan on grill to reduce the heat from reaching the ribs. Remember, your thermometer may not be correct and the temp is much higher.

As for smoking after the oven; as the meat cooks it becomes harder for the smoke to penetrate. You may get smoke flavor, but it will be limited to the top of the ribs.