I’m still learning members so I can’t tag some of them, hopefully someone else can. There are a few members who work at keeping Cornish X longer than just to butchering age.
I vote for Build, then. You need to make many modifications to attempt to get your Cornish crosses to live longer than 4-6 months. You’ll want low ramps and low roosts, and as many ways to try and keep them moving to food and water to keep their weight off so they can survive longer.