Definitely BG first. I'd concentrate on moving bigger BG from the stunted BG pond for now. If you get a late spawn out of them (likely IMHO that stinted 4" BG will be able to do that), then 6" LMB should have plenty to eat if you transfer them into your pond in a couple months.

What kind of numbers are you contemplating?

"Live like you'll die tomorrow, but manage your grass like you'll live forever."
-S. M. Stirling
[Linked Image from i.pinimg.com]