Tecohorn welcome to the PB forum. Start with your goals and work toward them. I assume from your post you want large BG and a few big LMB.

Either a classic LMB crowded pond or an all male BG pond with a few female LMB will do that.

But lets start with your first question. Over time (how long a time is a unanswered question) a stunted population of BG or LMB will select for that genetic trait. How many generations that takes is a very good question. There are a number of stunted BG threads here to read. It sounds like you have what I described to GW last week due to removal of your big BG. Here is the link/text.

http://www.pondboss.com/ubb/ultimatebb.php?ubb=get_topic;f=20;t=004456;p=2#000018

My thought is the way to fix this is while the water is down and the LMB are feeding help them out by seining or trapping out some small 3-5 in BG and add them to the other pond (if it could use them). Then add some new genes by adding about 50 adult CNBG from Todd when he brings the GC. The big CNBG will add genes plus suppress spawning by the small or stunted ones which should help their growth as well. A few adult RES would help also.

Feeding is a fertility add on as is fertilization. Each raises the productive capacity of the pond. Taking one away after using it for a while often results in to many hungry fish with not enough food. They can be mixed and matched and substituted to get what you want but it takes time and experience with your pond to get there.