I've got what appears to be a "sporterized" 1898 US Krag on the way to me~~~might be one of those infantry models cut down many years ago to carbine length. It utilizes the original stock (also probably cut down) and I see where the magazine cut-off lever used to be~~~it is missing, of course.

My question: how hard is it to re-install the cut-off? I can
get a cut-off assembly, but I have no idea on how to install
it. Is this a job for a competent gunsmith, or is it a job
that I could perform myself?

I will greatly appreciate your help. Thank you!