I would not run a pond/lake in these parts at 800 lbs per acre especially a shallow one with out aeration. To much chance of a DO crash with the resulting fish kill. That is 30,000+- lbs of fish in yours. Half that amount is plenty.

I would suggest that you look on the forum about whether you want pure Flas or not. Some for cross breeding would be good but for catchability you should check on F-1s and some northern LMB to go with some Flas. The further north the less well Flas perform wrt reaching their genetic potential. To far north and they die during winter. F-1 adults should be easier to find.

I anticipated you would run into this problem. That is why I suggested going ahead with the small BG growout pond. In the event you can't find enough adult LMB (assume you only find 100) then stock BG/RES mix (2in) into the BG pond along with a few hundred adult CNBG and some FH , ASAP. Feed them and in the early fall add 800 4-6in feed trained LMB into the BG growout pond keep them there on feed until March and then move them and the BG into the big lake. That should do the trick. Keep a few hundred BG/RES in the growout pond to replenish it.