Hi RoseMarie,
I have some recent experience in cockerel selection and this is my advice, for what it's worth. You want to breed from your best boy, but all will have faults, even in good lines of SQ BA's. So, you need to understand that breeding is about balancing 'faults' from either side. eg. try not to breed 2 similar faults together or you'll magnify the fault. I'll try to keep this super simple -
* reject birds which don't fit what a BA is - any with any feather color than black, some white in younger birds, and yellow in chicks, of course.
- any with legs other than black or slate grey
- any with eyes other than black, or dark brown at a pinch
- any with obvious deformities other than incubation caused ones
* look for - white soles on feet
- white toes
- dark beak, preferably black
- well-formed comb, with least number of comb points, less than 6 preferably
- size - a good BA is a big solid bird
- conformation - it's a bird of curves, no sharp angles from side-on. See my avatar
- note the full tail on the pic of my boy posted recently. Compare with the bird whose tail you show here. Pick a bird with a tail like my avatar side-on and my bird from top
view. This is a big ask from utility stock!
This is just somewhere to start and it's much more complex. If it helps whittle down your cockerel numbers that'd be great.
Cheers Geoff