Dick,
I don't own a Model 40 or 45, yet, so I did not want to be first to reply. However, I have one or two relatively high slots on the priority list for either, and I have watched prices and parts over the years. Like any old, small-production and less-than-popular rifle, parts are difficult to find. The most common parts source is cannibalized rifles, up until recently found on eBay.
New replacement stocks are available from various stock reproduction outfits. Original magazines, especially in 30/06, are relatively common. Butt plate, screws, swivels and some sights will be common to M99 rifles of the late 1920s through 1930s. The Lyman 40S receiver sight is relatively common. The trigger guard, bolt, and trigger group parts will be hardest to find.
Having the '40' version instead of '45', means a non-checkered stock (reproduction) and no receiver sight are proper.
Just how 'deep sleep' is this rifle?