Don,
I don't know about calculating the MOI of 2 oz over the length of 22 1/2" of barrels. But my experience suggests that the money to remove .010 out of the bores has a higher MOI.

I went thru these calculations and weighed the cost/benefit on a 32" Win 101 years ago. It had screw-ins, so the limit was about .010" out of the bore before the chokes became an issue. With such a small change in weight, I couldn't rationalize the cost. I just bought a 32" Beretta Gold E with very light barrels. Those new barrels came with a new action too. It was a much better move.