Mainspring modification

[poker]

I was replacing a broken mainspring with one that I found that should work fine, except its about 1/4” wider. Also the original was beveled along its length, I imagine to lighten its action.The new spring is a little thicker too, so I might have to bevel it a little more than the old one?
What would you recommend to narrow it up and bevel the edges without having to re-harden and/or re-temper afterwards? Advice appreciated

 

[64Springer]

Grinder and or Belt Sander and Water.

Lot and lots of water.