Shotgun smithing question?

[Mr. 16 gauge]

I'm looking at used O/U and SxS shotguns. I would like this gun primarily for upland hunting, so I would like open chokes (I.C. & Modified) on the gun, and I prefer 26" barrels. I hunt grouse & woodcock, but would also use the gun for pheasant, quail, rabbit, and chukar.
However, there are a lot more guns out there with tighter chokes (M &F) and 28" or longer barrels. Since there are more guns to pick from, prices are a little cheaper. My questions are:

1.) How difficult and how much (roughly) would it cost to open tighter chokes on a double barrel gun and

2.) how difficult and how much (again, roughly) would it cost to lop off a couple of inches of barrel (and have it done correctly!

My second part of this question is that I reload, and have made "spreader" loads in the past, both with the "X" inserts and the golf tee type inserts. My pattern testing indicates that they do open up chokes somewhat.
Would it be worthwhile to forgo the above mentioned smithing and just reload 'specialty' ammo for that particular gun?
Thanks in advance for your thoughts/opinions.