What I would do is take a turret cap to a big sporting goods store and see if it will fit a luepold, Burris,or any other scope that has a target knob style turret.
If you can find a generic knob that will fit your turrets then you can easily make a BDC knob out of it by a couple of different methods. Brown dog, 4kd horn and Abinok have computer programs to make a cover for the dial. Or you can use fingernail polish to cover up the generic numbers and then use a sharpie to inscribe your yardages.
Half time and it is Alabama 7 Texas Tech 3 ROLLLLL TIDE
The Smokin Fur Rifle Club