I've had more than a few of the Pedersoli Bess and Charlie kits where their touch hole was partially drilled into the face of the breech plug.
Here's the breech plug for a Pedersoli '66 Charlie - I was pleasantly surprised to see that its breech plug face wasn't desecrated and the touch hole was perfectly drilled within 1/32" of that plug's face ...

Here's the breech plug for a Pedersoli 2nd Land Pattern Bess ...

Usually I open that plug face channel a bit for ease of cleaning out and better ignition. But instead, would grinding the plug face smooth and thus removing that 3/32" deep channel be structurally okay to do?