THAT looks GOOD.I always tapered the upper limb AFTER it was forged and be sure the closure is tight.What you are doing will work and I hope my explanation yesterday made at least a little sense.Showing and explaining,VAST be the gulf that separates them.After it's forged and flat,make and install the link in the tumbler arm.Rotate the tumbler arm to the FULL cocked position and place the spring on the link and mark the place where the pin will go and drill it with whatever drill is appropriate and then,heat and open the spring until it's about 6mm below the link in the lowest and fully extended length and a curve in the lower limb as well as the upper and this will be determined by experimentation. Harden the spring,temper it and install it and see what you have by slowly flexing it while connected to the tumbler by
lighly securing the square shank in a vise and rotating the lock plate.
Bob Roller