Nice rifle but, I'd have to darken the metal for my taste. I'm a blue steel/walnut kind of looney. grin
As far as powders go, 4350 will give you everything you need but, I've found the 7x57 works well with any powder and used burning rates from IMR-3031 through MR-3100 with great success.

Shew me thy ways, O LORD: teach me thy paths.
"there are few better cartridges on Earth than the 7 x 57mm Mauser"
"the .30 Springfield is light, accurate, penetrating, and has surprising stopping power"