I want to shoot 2-3/4 out of a 2-2/8 gun

[Tom]

Any body doing this ? It would just be easier. I have never reloaded before so I am just trying to gather info at this stage.
I have a 12 guage with 2-5/8 chambers, the front of the chambers on the bottom measures .060 that's pretty thin. I believe it came from the factory this way.
I'm thinking of 7/8 oz loads at around 9,500 psi or so. This would only leave 1/8 of an inch of shell in the forcing cone. And considdering this is an old gun bored out to .750 instead of .729 I'm not sure this would be a big deal. Of course I could be totally wrong.
My alternative thinking would be to cut the cases down to 2-5/8 but I am not sure how to handle the wad, I have been told not to modify the recipie so I'm not sure how to handle this.
Could I have some advice on this, I'm sure I'm not the first down this road.
Thank you, Tom