IL -- Where to start with this thread ? Good advice so far but your goal is different so the application of that advice is also IMO.

HBG have two hybrid vigor advantages and two outbreeding depression disadvantages. Initial growth rate and CATCHABILITY are the advantages while high male % (between 67% and 98% - IMO 67% is an aberration expect 90% ) and outbreeding depression in the HBG offspring (you don't get many anyway as almost all are male). The initial growth rate advantage is short lived and soon the MALE BG catch up and may get bigger. But the half BG population that are female don't catch up. So in a standard BG vs HBG comparison the HBG population has greater avg size. Most studies about HBG repeat that the major reason for them is the second hybrid vigor trait - easy to catch. They can easily be fished out. It is unclear if HBG can backcross with either parental (conflicting studies) all by PhD fishery science teachers/researchers. I tend to agree with Theo that they can but in a limited manner. The only way to deal with the outbreeding depression in HBG offspring is to be sure they are eaten or killed off.

IL there is no magic bullet for your situation. To get the pond you want requires knowing how to achieve and maintain a balanced fishery. You can do that with some work and knowledge and experience. Don't be scared of the situation or the "what-ifs" as it/they are fixable.

If your LMB are growing and in good condition and the GSF seem to be under control then I would add the 1000 3-5in. BG. I would look for 200 adult 6+ in. HBG and add them after the BG spawn. Try to catch out the HBG over an 18 mth period (not hard if folks are fishing for them with live bait). In the meantime learn how to asses and correct pond balance matters so you will have a better feel for the what next questions. If there are GSF and BG in the pond you will get a few natural HBG most of which will be eaten. Over time the BG will out reproduce the rest. I would not substitute HBG for BG in the 1000 as you need the reproduction from the BG. If over time the BG seem to be getting small it is easy in a pond that size to trap or seine the numbers down. If the LMB have gotten control of the GSF , as noted, you will need the BG spawn capacity to feed the LMB. AS you want a catch and keep HBG/BG status you can learn how many HBG to add over time but I would only add adults. Your LMB plan will require you to take out some small LMB (8-13 in)to keep balance over time and to keep the avg size up.