How different would the bottom metal be for a .404 Jeff if built from a .375 H&H Win M70 SS Classic?

At Sound Metal Products, we make them wider from the shoulder back...that is ideal, but involves rail work...It SHOULD feed 404's OK..not perfect, but workable in the original configuration

I have one on a Model 70 LA and a Winchester box with the "windows" in the sides worked fine but, it still needed rail work. Feeds very smoothly and reliably now.
I forgot to mention that I cannot afford Duane's bottom metal or that is what I would have used. I did buy the Williams "Oberndorf" floorplate and guard but it was only $160.00.