Something to check for are sprigs on his comb, which are undesirable for breeding, and split wing.
Are those common issues in the breed, or are you seeing something in the photos that makes you think he might have these issues? I'll have to check him closer tonight.
Nice to see someone following good flock practices, and quarantining! Good Luck with him, send more pictures as he develops!
Only takes one bad experience to learn to do it right. I purchased a number of BLRW hens/roosters from a breeder near me. Turned out they were all sick, and I'm sure the breeder knew that when they sold them to me as I heard the birds making "funny noises" on the drive home, but didn't realize at the time what those noises were. I called to ask her about the noises and was given a song and dance about it being stress from the transport. I had a pen just for those birds that was away from my main flocks pen, but since I was free ranging my main flock they of course headed right over to the BLRW pen to check them out. Ended up having to cull all of the BLRW and a large portion of my main flock. Ultimately predators killed the remainder of my flock, which sucked but may have been a blessing in disguise since I had to start from scratch, and haven't had any health issues since.