I've said this before, probably even on this thread- You are not going to get good results using hatchery stock birds. The weights reported on hatchery web sites are for standard bred birds which they do not offer. The birds will be smaller.
I've no personal experience but have read on the BYC...
Hatchery birds are bred for egg production. You can not be guaranteed they are even pure lineage. When a "breed" that should have red ear lobes has white and red ears with a body that looks more like a Leghorn you start to suspect Leghorn was in it's lineage yet it's buff and looks somewhat...
Here is a good article about how to select birds for meat quality. The fundamentals herein can be used with either improvement of a breed or in creating a strain.
https://livestockconservancy.org/images/uploads/docs/ALBCchicken_assessment-1.pdf
another on ongoing selection criteria-...
I didn't specifically read it but believe as of yet you don't have any birds. This is of great advantage to you. Take your time and get the BEST stock you can obtain/afford. Your posts seem to me that you are selecting breeds based on descriptions yet are planning to obtain hatchery stock that...