If we were going by show rules, a bird that isn't a recognized variety could still be entered and scored, but in a show it couldn't win anything higher than Best of AOV. We'd have to discuss how we wanted to handle that with judging.
Anything under four months old is really hard to judge to SOP, because the birds still have a lot of filling out to do. They could for sure be entered, but if they're in the purebred category, they won't score as highly as a mature bird will, if we judge to the SOP.
I'm one of the judges - we judge to the American SOP. Provided we decide to do this the same as last year for the category of purebreds, faults would detract from the bird's score, just like in a real show, but as long as it's not an outright DQ, the bird will still get judged and scored :)