"What I would do is get apiece of 5150 spring steel flat bar and cut the basic outline of the spring out from the bar. Then, heat to red and bend, file and grind to the correct shape then heat treat to form a brand new spring."

I was thinking much the same thing. The spring shape doesn't appear to be so complex that it couldn't be relatively easily duplicated by any competent machinist or gunsmith. But it probably would not be a cheap job if you can't do it yourself. I have made similar springs myself (but not for a Ladysmith).