Hi Edwardo. Welcome to Pond Boss!

I think anything other than 100% elimination of the green sunfish will cause you more problems in the future. I don't think stocking the larger LMB will get you down to zero GSF.

I also think you need to repair your outlet pipe before you start spending money and time to stock your pond for LMB and BG.

Therefore, IMO now is a perfect time to drain the pond down and then rotenone.

Rotenone is a restricted use pesticide in many states, so it must be applied by a pro in those circumstances. (I don't know the rules for AL.) I don't know if the $2500 bid is reasonable, but there are some pond management people on the forum that do know the appropriate price.

How deep is your pond? Some of the Alabama catfish ponds can be fairly shallow. If you are only going to draw down a few feet, then a trash pump is a viable option. If you are going to move a very large volume of water, then it might be easier to just set up a siphon.

Do you have an area that is a few feet lower than the bottom of the pond for the siphon outlet? If so, you can use some of the cheap corrugated flexible pipe to siphon down your pond. (Or make a nice siphon out of PVC if you just need to go over the berm/dam.)

A LMB/BG pond in Alabama that is starting with a clean slate should rapidly grow those fish for you. If you fix the outlet and rotenone soon, you can probably still put in some fathead minnows this fall so you can stock the other species next spring.

Good luck on your pond rehab project!