You may want to look into some of the other varieties that are raised as a quick dress chicken. I often see people advertise Cobb as a quick cornish style bird and if you research with google, you will see mentions of several kinds of birds like Corndells that are used in organic free range outfits.
With all of these birds, your breeding stock has to be fed a lower calorie diet to curb excessive growth, like one would do with bb turkeys and they are usually a.i. for fertile egg production.
I have found red sexlink males grow quite large in 16 to 20 weeks. With them, you are producing known layers that are easily sold and pretty meaty males. Caponizing is a lost art that I eventually want to learn more about, as I think that it would make unwanted cockerels have a purpose again and produce a more flavor filled bird.
FYI I have raised out cornish X's, the males grow too large to mate with the broad side of a barn and their appetites are ferocious. If you cross the hens with just about anything else, we did notice the chicks were noticeably larger. I have some that started laying at 4 months and they are now 2 1/2 years old and still waddling around.