As has been pointed out, CE 250s are .400 spine shafts. They are rather heavy to begin with, about 10 grains per inch or so if I remember correctly.
In the example you give, you're only talking about changing the up front weight by 50 grains. I think you're in the ballpark with either. One is likely to work a little better than the other. Since you already have the 125 grain heads, buy a few 150 or 175 grain heads and see how that works. Your overall arrow weight will be heavy enough regardless.
I believe 3Rivers, and probably some other vendors do sell field point test kits containing several different grain weights..