Re: Depending on your replies, I may have to quit before I start.
I believe that you are worrying about something that you don't need to. You seem to be assuming greater genetic effect than actually can have. You overestimate the effects that one set of genes may have on another.
Isolation is relative. No colony of bees can exist 9 years w/out there being other colonies nearby. Nearby meaning w/in the maximum distance which swarms fly away from their parent hive. And also w/in drone congregation area range. So, just because you don't know about them they are out there somewhere.
I wish you well w/ whatever swarm you might gather off of this feral colony, just don't get your hopes and expectations up too high. One thing I would bet on is that they are swarmy. That's how feral colonies survive, survive mites.
"It's not what you look at that matters, it's what you see." Henry David Thoreau, Mark B