Oof, I got busy and this thread went crazy! I'll try to catch up on everything later, but here's my plan at this point:
I just got my third group of ranger chicks - I have some from two different hatcheries, so far they seem the same. Out of the older ones I have nine pullets and one keeper cockerel. A couple of the pullets aren't as nice, so I'll probably cull those once I decide which to keep from the current batch. I got 25 this time, so I should have plenty to choose from! Hopefully another nice cockerel too. The other I was going to keep committed suicide the other day

Aside from that they've been really healthy though. The oldest are about 12 weeks, and as big as my standard layers. I just moved them into a separate coop; since they're supposed to start laying young, I'm hoping to get a small hatch in the fall to at least make sure it's going to be worth it to feed them through the winter, and I want to make sure they're only bred to the Ranger roos and not my Jersey Giant.
As far as outside breeds, I've decided the only thing I'm going to introduce is Buff Orpington. They're nice heavy birds with good mothering abilities, plus they'll still pluck out clean. I'd like to move the project birds to a different color in the long run, so they can be distinguished from the hatchery rangers. and I've always loved buffs. I'm trying to select lighter reds to keep which are already pretty close to a dark buff - especially when they're young. Buff is a different gene though, so once I bring that in they won't revert back to red. I have two buff hens in the new pen - one of whom raised my first batch of rangers - and two red hens that I think are half buffs, and look just like the rangers. One of those is a proven broody, and the other had a full sister that was (lost that one of course.) I'm going to attempt to track which hatching eggs are from which hens via food dye on the cloacas, which has worked for me on my layers, so hopefully I can tell which are making better chicks and cull the ones who aren't. Although if I have multiple roosters I won't know which ones they throw - unless I set up another breeding pen, but I can't keep adding more while still giving them room to forage, so I think I'll just swap out roosters whenever I get one that looks better. Hopefully a nice buff rooster in the first or second generation so I can bring the color in early, rather than down the line when I've refined it more.
So far I've been able to raise all 3 groups under broodies - with two co-mothering the newest 25

I'll put as many as I can under hens, whether or not they're actually part of the breeding project, but I know in order to have enough to choose the best to retain and still have genetic viability I'll need to incubate some larger groups. I'm hoping to arrange a partnership with someone who wants to raise meat birds for them to grow them out and keep the culls for butcher in exchange for me choosing the best breeding stock to take back.
tl;dr my goals are:
Large, fast growing birds that still have longevity as breeding stock, as well as hardiness and good foraging ability; strong inclination towards broodiness - hopefully a couple clutches a year per hen. Plus buff coloring, eventually culling out all the reds. I'm toying with names based on that - does "Olympic Golds" sound too much like a proprietary hybrid?
MTA: my birds will NOT be proprietary, trademarked, etc. I want to create true-breeding birds that people can raise themselves. However, I will not be selling them as such until they're well established and consistent; just as ranger crosses for meat.