I think the body of the bolt is original, but the bolt handle is a replacement.
It was a gunsmithing option that I remember seeing advertised (or similiar ones advertised) in 1950s and 1960s issues of American Rifleman magazine.
That thumbhole stock is very interesting. I've never seen one like it in the time frame that it appears to be from -- white line spacers like that were all the rage in the 1950s and 1960s.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.