length of benchrest stock

[Hank45]

I am an offhand shooter. The length of pull on my rifle is 13 1/2 inches, which for me is excellant. My question is does a benchrest stock for this rifle (1885 winchester lo-wall in .22 hornet) need to stay the same (13 1/2) be longer by how much or be shorter by how much? Thanks for your answer Hank45