A much easier trick for straightening soft wire is to put one end into a bench vice and pull on the other with a pair of vice grips. Not only will you get the wire perfectly straight, but you will work harden it at the same time.
If you don't have a bench vice and vice grips, you can wrap either end around metal rods, put one under your feet, and pull the other with your hands.
I would be worried about heating galvanized (zinc-coated) metal with a torch. Metal fumes are some truly nasty stuff. if you do this, be absolutely certain to do it outdoors and make sure you are upwind. If there is no wind, run a fan.
Personally, I am not a fan of soft wire to begin with. You can buy spools of music wire on amazon for the same price as soft steel from the local hardware store. I paid about $7 for 275 feet of 0.037 (16 ga) music wire. This is the perfect size for the holes in 9 gram servos. Straightening coiled music wire is certainly not fun, but it is really not all that difficult either with a little bit of practice.