Flexplate is not fits the torque converter

What? The answer is the ATP Z-332!
So I've bought it! :) and this is the 4th flexplate and it's not fit :) it's 10` and I need 11`. Ordered the B&M 10236, I know it's wrong weight, I know it's for 360 and not for magnum but this is the best choice I have. Need your advice here - what if!!! I'll cut a small piece on the opposite side of the "cut" the 10360 have? it should balance 500+ grams, I need 314 grams, so if I'll cut a small piece - will it help to be closer from 500 to 300 grams I need for my magnum?