Decisions are good, they clarify your goal and help with the steps needed to reach it.
However, I think you're both overcomplicating and underestimating here!
Since you'll be basically just redoing your current body, all you need is the neck pocket template for duplicating it. You don't need to study models that "almost use the same wizard neck" since you already have the exact model. Take a piece of MDF or plywood and draw the neck pocket using your neck as a guide. Make the template long enough for adjusting and attaching, and also for maintaining the center line. The most important thing is that it fits snugly around your neck heel. Then measure the depth of the original pocket at both ends to find out the potential neck break angle. If there is, simply attach the template in the same angle using wedges.
Then, as @curtisa said, route the neck pocket into the body blank before cutting the final shape.