I would only recommend stocking a pike or a muskie in a situation where the owner wanted a pike or a muskie. In my opinion there really isnt a wrong or a right way to manage a pond, just 1000's of options that all depend on 1000's of variables that all boil down to what the owner wants.
From what I have gathered, Eyedoc1 would like to eliminate the green sunfish as fast as he can without killing out the pond and starting over. There have been several really good suggestions, all of which would indeed help, and I have a few of my own.
In Missouri, fishery biologists are everywhere and offer many services to assist you in achieving your perfect pond. If one is not available in a time frame suitable to your need, I would call up Shawn with Midwest Lake Management to come over and give your pond a full lake audit. On site, he could diagnose and prescribe and help you formulate a management plan that suits your goals, timeframe and budget.
Also a few suggestions I might make that havent been talked about yet would be to implement a fish feeding program to speed up the growth process and gain you a few years growth as well as potentially adding some Hybrid Striped Bass to clean up the mess. On a feeding program, they will grow faster than any other gamefish you could stock in your pond. They would clean up the greenies and then if you didnt want to continue with them you could simply catch em, eat em, and move on with a new project. They dont reproduce and are fairly easy to catch once or twice, they do get smart though!!!
If your not long gone already, shoot some more questions and definitely updates back this way. I bet ya there are some green sunfish articles in the back issues of the magazine as well?