Winchester made a Model 1910 semi-auto in .401 SL. The cartridge, if you've never seen one, looks like a .30 Carbine on steroids. Drives a .406", 200 grain jacketed bullet at 1600fps to 1915fps depending on the powder used. Unique or 2400. I have data should you ever get that far. E-mail me if you want the data anyway. firstname.lastname@example.org
Have one loaded cartridge around here someplace too.
What condition is the steel in? If it's heavily rusted and pitted, restoring the rifle likely isn't worth the effort or expense.
Try this guy for stock parts, but I wouldn't hold my breath. He might know of a source though.
Jack First, Inc.
1201 Turbin Drive
Rapid City , SD 57701