Sounds like a neat project! How long has it been un-managed? If a long enough time, then any monsters would be near the end of their life cycle, and stocking new smaller fish would have to take account the predation. If they have been stunted long enough it might be better to start with new genetics.

Is mucking it out after draining a viable option? It could be pushed (maybe) on the cow fields for free fertilizer. That would also help gt rid of the hyacinth seed bed at the same time.

Let the water go between both but maybe a spillway between them and make the smaller one just HSB and whatever LMB go over the spillway, make the bigger one a trophy LMB lake!

LOTS to think about.