Doug in my opinion the 30" barrels are a good thing, 32" even better and more scarce. As far as the chokes I would not worry about that since you have now started reloading you can make spreader loads if you have to, but first shoot it and see how the chokes perform.
The bores as Charlie stated are smaller at .650 and were changed in the mid thirties to .660. You can buy 2 1/2" Cheddite hulls with Cheddite 209 primers from Ballistics Products (when they have them) for around $23.00 a hundred. In my opinion I would not lengthen the chambers but leave them at what they came with 2 9/16".