I'd like to thin and reshape a crank arm. I've got a Shimano FC-6207 left crank. It looks to me that the Dura Ace FC-7400 is made from the same forging and is machined down a bit and fully polished. I'd like to thin the FC-6207 left arms front face and contour the back to match a Ritchey Logic right side. I'd be using hand files and abrasives.