I realized the loads would have to be suitable power and load size, so i was just wondering about shooting the lighter hand loads or even factory loads...1oz for the range and 1, 1 1/8 for upland. I was always under the impression that 2 1/2" shells were three times the money plus with the way prices have sky rocketed in the ammo world it would even be tougher to get and even higher priced. So basically as long as you run the lighter 2 3/4" shells you might be alright without having to modify the shotgun. I guess if the shorter shells are fairly easy to get it wouldnt be an issue? I already buy duck/geese loads by the flat as my dogs and I guide and I end up shooting lots at a friends private duck lake up on Sauvies Island. Lot of the members have top shelf shotguns but are not the best shots!
You ask reasonable questions.
1.) The gun is better now than it will be after any modifications. Modifications will destroy the gun's value.
2.) Nothing ever got stronger by removing metal. Shadetree American gunsmiths have caused more danger and destruction of value by lengthening chambers than they've done good. Equally unadvised, you can shoot a 2.75" shell in a 2.5" chamber. It's very dumb because it causes a pressure spike, but people do it. Slightly less dumb, people will lengthen the forcing cone to shoot 2.75 low pressure shells in a 2.5" chamber.
3.) Presently, the cost of 2.5" shells is an astounding $12. I believe the cost at present of 2.75" shells is roughly a cent less per box.
4.) 2.5" shells pattern better.
5.) 2.5" chambered guns are about 1.5lbs lighter
6.) 2.5" chambered guns are worth considerably more
7.) Guns that have been lengthened from 2.5" to 2.75" become virtually worthless, particularly if they are not re-proofed in England afterwards
If you want overweight guns with lots of recoil and poor levels of refinement, just buy a new 2.75" gun. Doing such conversions to this gun is equivalent of buying a ferrari and putting a trailer hitch on the back.