Sounds like an amazing body of water. I would definitely begin a close management program but start by taking measurements. All BG and LMB caught should be weighed and measured. You can then run relative weights on them. As has already been said, your lake has classic signs of being bass over populated. In northern ponds and lakes this is very common.

Immediately begin removing every single LMB of every size you catch. You honestly can't remove too many in my opinion...

I am OK with the stocking of tiger musky. Your lake is a great candidate for them compared to most. As has been said, they'll eat what they want, but what they eat should do more to help than to harm in your situation. To help spread out the cost of stocking the TM, I would recommend you stock 6-8 per year over the next 3 years. I would then stock 3-4 biannually there after.

This stocking strategy should help thin out your 10" LMB problem and also thin the carp population as well as create a unique trophy TM fishery. There are a few sources of TM in the upper Midwest, finding ones in the 15" range would be ideal. They should be available this upcoming fall. Begin sourcing them now...

The big key here is to remove large numbers of LMB though. That will mean lots of effort being put into catching them. You'll likely see relative weight values in the 70's or 80's starting out. Your goal should be to get them into the 100 range. This will likely take 5+ years of dedicated LMB removal by angling and some assistance from TM predation.

As you see relative weight values increase and push the 90's, I would then consider the stocking of additional forage. A big question for me is, does your Lake connect to any other body of water? You mentioned underground springs, but what about small creek, stream, etc? Only during high water events or always? This does factor into recommendations I would give. If it doesn't connect to any other body of water, I'd consider stocking new BG and after LMB numbers are controlled even some new LMB. Decades of isolation could mean an infusion of new genetics would likely be a good thing.

I would also target the catfish hard and remove all caught without exception. As has been stated, they do compete directory with the bass for the limited resources available.

Your pond being an old quarry does create a unique challenge in limited shallow water refuge areas for your forage of all species. Adding structure will certainly be a good thing. If aquatic vegetation hasn't taken hold in your lake yet, it likely never will.

Are you willing to begin even a modest feeding program? If do, further advice can be given if that is an option.

Best of luck!