Will the original Winchester 1886 buttstock fit the new ones by U.S. Repeating arms and Browning without any mods?
Am looking to change U.S. Repeating arms take-down 45/70 from a straight grip to a pistol grip with a straight butt but all Winchester Parts has is one with a curved butt plate.

Pistol grip requires the lower tang bent in a curve to fit, so I'm pretty sure it won't work without significant modification.

I've got the curved lower tang and the lever for the mod, was hoping to luck out with an existing stock.
I don't know how much Winchester and the Japanese followed the original receiver specs in the remakes.

I have fitted new made Win stocks to Browning Jap 86 rifles; long ago, but as I recall, they were close enough to allow for a good fit.