Grinding the shell holder can lead to pulling the rims out, breaking the shell holder. Shortening the die is the better solution and is not really hard, I've done it several times. If you turn the loading die in a 7/8-14 threading die, it will turn true, if you center it with the tailstock center while tightening the chuck. A sharp carbide tool will cut the die, facing it off from the center out. It will "squall" a little until you get through the hard part. Don't forget to radius and polish it at the end. This may be all you need to do to be able to use the standard dies. If you make the die a little shorter, you can "fine adjust" it to fit the chamber.
Mike