Let me preface this by saying I have tried non of the solutions. On the other hand, for reasons having nothing to do with guns, I have studied about springs probably more than was good for me.

The strength of a flat spring is directly proportion to its width. Narrow it by 50% and cut its strength in half. Thickness is a much more complicated process. The relationship is "non linear". Calculating the strength reduction from a little thinning will be difficult. Bending changes a spring's "pre load" and also it's geometry, so the result will be trial error. Given those choices I'm pretty sure I'd grind a little off the sides.

Ed