I used to be a spring maker but not in the term commonly associated.
Music wire is a bitch to work with, we/i only used it for jobs where no quality was required.
Beter off if you can obtain decent spring steel annealed, make a mandrel up and wind it on leaving extra for tangs etc.
The problem is new spring steel isnt as good as old stuff even though supposedly share a similar spec or the old EN grade.
Its trial and error with the hardening try a few test pieces first. May have to harden and drop in cold water to get the strengh/hardness and temper by burning whale oil off or to straw after. hardening, really is trial and error.