The problem is that Grady's lower hopper bar is so badly warped that it allows coal to drop on and smother most of the firebasket. The thought was that maybe the hopper could be completely removed and the stove could be run as if it did not have a hopper. Coal would be shovelled in after each shake-down and banked as needed.
My biggest concern was that the exhaust gas would have easier acces to the top of the stove where the filler cap is. However, if the cap has a good gasket, it should seal in the CO gas. Even with the hopper in, I'm sure some CO gas is in the hopper, it just has to filter its way up though the coal in the hopper, just as combustion air filters its way up through the coal in the fire basket.
As long as you have a good gasket on the filler cap and you have working CO detectors in the home, I would give it a shot until your new lower hopper bar comes in.