I checked. It is in "More Single Shot Rifles". Looks to me like you could grind a S&W mainspring for a hammer spring and bend up a piano wire paperclip deal for the trigger spring. Tempering springs from scratch is entirely too tricky for me. You can either make the firing pin from drill rod which is hard enough already or adapt one of the shotgun firing pins from the kit that most gunsmiths have.

If you try regrinding a spring, shove the part that flexes into potato and anneal the butt so you can drill a hole through it.