It always perks my interest when someone says they have big bass! If you are willing to spend the money for the survey, the fish kill and the restocking are you really willing to take a chance and not fix the dam? Risk/Reward?? If you're there for only a few years and you already have 7+lb bass, invite the scout troop over for the weekend tell them you will donate a dollar for every pound of sunfish they pull out then add some more bass and bluegill. Enjoy the big fish you catch, take some pictures and when the dam does break you'll have a chance to start all over from scratch.
I AM NOT A PRO, THIS IS NOT PROFESSIONAL ADVICE, just hate to see BIG fish lost.