Madagascar Gamefowl, how would one know how pure one is by looking at it?.......

Greetings fellow BYC members. Recently I have ordered 8 Madagascar Gamefowl chicks from a private breeder. If one says they are a "great line" and are "imported" from a while back how would I know just by looking at the birds, if indeed these things are true? Although I do understand what "line" and "imported" mean when talking poultry or game can some one give me some insight as what characteristics to look for when breeding these. My intentions are to keep this breed as I understand they are not a rare breed but not a lot of people are interested in this breed to keep it.
Also, there is not a lot of information on these so I would like to hear other peoples experiences with them.
My questions are not specific because I have come to realize when people breed chickens their selection in breeding may not be the same priority as another breeder. Certain features appeal to one and not the other. Which is like one of my vague questions, why would one feature be more appealing to one breeder and not the other.
So back to my original question, what is a Madagascar Gamefowl suppose to look like?
I would like to thank everyone in advance and please be generous with your advice and information.