^^^ I will try for a very Nathan-esque answer. If you managed to get a 3" swedge along the length of the spine, that is 1/16" deep by 3/16" tall on both sides, you will remove ~1/8 of an ounce. Not very much at all.
Put another way, on a 20oz knife (I just picked a number...) you are looking at 10% of that to grind off 2oz. Take your knife and draw 4 lines on the blade, then imagine grinding off to the first line.
Balance is about weight distribution. To get the most noticeable difference you need to remove it as far away from the balance point as you can. The new handles won't make a lot of difference because they span (a little bit) in front of the balance point.
With your stated parameters, you are trying for a little lighter blade/handle heavy balance (removing more weight from the blade than the handle).
Just as an experiment, try this...get some fine gage lead solder wire. Pop one scale off and put some in the back pocket of the tang. See if adding weight to the back end gives you the new balance point (albeit at a heavier weight overal) you are looking for.
TL,DR; no, you won't get 2 ounces with a swedge.
All just my musings/opinion and I could be stupidly, glaringly wrong.